Psychotherapeuten-liste-tuebingen.de - SEO Checker

Sign up for free! PDF Export
Overview of the SEO Check
Meta information
91% 
Page quality
61% 
Page structure
58% 
Link structure
56% 
Server
100% 
External factors
0% 
SEO Score
Response time
0.26 s
File size
162.00 kB
Words
4224
Media files
0
Number of links
6 internal / 96 external

Task list of SEO Improvements

Meta specifications

Title
(Critically important)
Psychotherapeuten-Liste Tübingen
The length of the page title is perfect. (310 pixels out of 580 max pixel length)
There are no duplicate words in the title
Meta description
(Critically important)
Liste von Psychotherapeuten und Psychotherapeutinnen in Tübingen
The length of the meta description is perfect. (422 pixels out of 1000 max pixel length)
Crawlability
(Critically important)
There are no problems in accessing the website.
Canonical URL
(Important)
https://www.psychotherapeuten-liste-tuebingen.de/
There is a valid canonical link specified.
Language
(Somewhat important)
Language detected in text: de
Language defined in HTML: de-de
Server location: Germany
The following language is defined by HTML: de-de
Alternate/Hreflang Links
(Somewhat important)
There are no alternate links specified on this page.
Other meta tags
(Somewhat important)
There is no rel next meta tag on this page.
There is no rel prev meta tag on this page.
Domain
(Somewhat important)
The domain name is very long.
The domain is no subdomain.
The domain does not contain non-latin characters.
Page URL
(Somewhat important)
No parameters were found in the URL.
No session ID was found in the URL.
The URL does not have too many subdirectories.
Charset encoding
(Somewhat important)
The charset encoding (UTF-8) is set correctly.
Doctype
(Nice to have)
The doctype HTML 5 is set correctly.
The doctype is placed at first in the HTML code.
Favicon
(Nice to have)
No favicon is linked in the HTML code.

Meta tags

NameValue
viewportwidth=device-width,initial-scale=1
color-schemeonly light
descriptionListe von Psychotherapeuten und Psychotherapeutinnen in Tübingen
robotsnotranslate, noarchive
langde-de
charsetutf-8

Automatically check psychotherapeuten-liste-tuebingen.de including all subpages at once!

Try for free
Guaranteed free of charge during trial period.

Page quality

Content
(Critically important)
Words from the H1 heading are not used in the page content.
The content of this page is too large (4224 words). Maybe the content could be divided into several pages.
There are 2 text duplicates on this page:
  • Duplicate: Liststraße 7 72074 Tübingen 01512 90 56 533 info@therapie-steiner.de a...
The average number of words per sentence of 9.04 words is low.
4.8% of the text are stop words.
Keywords used in the page title are also used in the page content. That's good!
225 paragraphs were found on this page.
No placeholders texts or images were found.
Frames
(Critically important)
This page does not use a frameset.
Mobile optimization
(Somewhat important)
No Apple touch icon is specified.
A viewport "width=device-width,initial-scale=1" is provided.
Bold and strong tags
(Somewhat important)
The usage of strong and bold tags is perfect. We recommend the use of up to 84 tags for this page.
Image SEO
(Somewhat important)
Alt text (alternative text) is correctly used on all found images.
Social Networks
(Nice to have)
There are only a few social sharing widgets on the page. Make your website popular in social networks with social sharing widgets.
Additional markup
(Nice to have)
No additional page markup was found.
HTTPS
(Somewhat important)
This website uses HTTPS to protect privacy and integrity of the exchanged data.
All included files are also transferred via HTTPS.

Media list

No media files were found.

Page structure

H1 heading
(Critically important)
Psychotherapeuten-Liste Tübingen
The H1 heading is perfect.
Headings
(Important)
There are 235 headings on the page. The amount of headings should be in a more proper relation to the amount of text.

Heading structure

Heading levelContent
H1 Psychotherapeuten-Liste Tübingen
H2 Nadine Greiner
H2 Sylvie Mareike Etrich
H2 Lydia Töpperwein
H2 Barbara Hinz
H2 Jörg-Peter Assmann
H2 Carmen Morawetz
H2 Lucie Sander-Wehle
H2 Manfred Kooistra
H2 Anette Kossack
H2 Anke Seitz
H2 Hendrik Janz-Frisch
H2 Melanie Hudemann
H2 Klaus Seiler
H2 Miriam Wolf
H2 Mario Fischer
H2 Reinhard Herold
H2 Gerd Schäfer
H2 Brigitte Schorpp-Heger
H2 Jakob Erne
H2 Selina Schneider
H2 Adelheid Noe
H2 Bernhard Leibig
H2 Ines Rießen
H2 Andrea Dolfen
H2 Detlef Hielscher
H2 Sebastian Denoix
H2 Corinna Grieshaber
H2 Vera Heuer-Jung
H2 Malena Schmidt-Riese
H2 Andrea Henzler
H2 Anja Assmann
H2 Annette Straten
H2 Dzeneta Wengenmayer
H2 Aiste Jusyte
H2 Eva Mack
H2 Christiane Schlotter
H2 Renate Hagenbuch
H2 Caroline Schröder
H2 Alexandra Haux
H2 Judith Kirsten
H2 Karin Malitius
H2 Lena Hasenmaile
H2 Reinhold Wolf
H2 Michael Steiner
H2 Julia Raabe
H2 Kathrin Stephan
H2 Sabine Stark-Feger
H2 Michaela Kunze
H2 Mathilde Fatke-Müller
H2 Julia Link
H2 Amelie Brinkmann
H2 Gabriela Baum
H2 Dietmar Heger
H2 Raphael Niebler
H2 Silke Wöhrmann
H2 Gabriele Albrecht
H2 Melanie Wahl-Mörk
H2 Stefan Geiselhart
H2 Angelika Hantke
H2 Evelyn Reinhard-Miltz
H2 Brigitte Eberspächer
H2 Katrin Klingler
H2 Laura Eder
H2 Ulrike Reber
H2 Angelika Walter
H2 Jan Hirn
H2 Christiane Kiviet
H2 Hanne Hermelink
H2 Monika Knauf
H2 Stiliani Andreadaki
H2 Patrick Böttcher
H2 Verena Friebe
H2 Klaus-Dieter Kleinschmidt
H2 Martin Jung
H2 Anne Koop
H2 Sebastian Wolf
H2 Dagmar Thomas
H2 Kathrin Ripper
H2 Dorothea Nicolescu
H2 Gabrielle Travers-Podmaniczky
H2 Daniel Broß
H2 Sabine Schumann
H2 Daniela Meile
H2 Kirsten Lukas
H2 Allique Goudriaan
H2 Birgit Trupp
H2 Martina Buchmann
H2 Gotthilf Steiner
H2 Ana-Maria Dorka
H2 Frieder Pfrommer
H2 Sigrun Schmiedl
H2 Jassen Halatsch
H2 Andreas Laurenze
H2 Susanne Ulmer
H2 Marie-Luise Waldhausen
H2 Edeltraud Putz-Meinhardt
H2 Verena Nölke
H2 Friederike Gundel
H2 Renate Krist
H2 Senia Mader
H2 Susanne Ziegler-Moroschan
H2 Birgit Baumann
H2 Mark Christian Uhle
H2 Reinhold Zeyer
H2 Bernhard Cerff
H2 Eva Maria Jäger
H2 Cathalin Schweizer
H2 Susan Noell
H2 Helmut Storzer-Braun
H2 Christa Schell
H2 Bernd Isensee
H2 Birgit Schwärzler
H2 Johannes Hub
H2 Susanne Stengelin
H2 Sophia Baar-Fischer
H2 Michael Feyerabend
H2 Jessica Anders
H2 Andrea Mayer
H2 Leopold Morbitzer
H2 Irmtraud Wettach
H2 Lara Berlitz
H2 Eva-Maria Kittel
H2 Kerstin Zinser
H2 Sebastian Menkor
H2 Martina Schittenhelm
H2 Martina Fischer
H2 Julia Graebe
H2 Andrea Jacki
H2 Miki Yamashita
H2 Wolfgang Kambeitz
H2 Hanna Smoltczyk
H2 Misericordia Romances Pujol-Schwarz
H2 Sibylle Koßmann-Böhm
H2 Katja Walter
H2 Simone Kambeitz
H2 Mareile Korte-Schraivogel
H2 Winfried Pohl
H2 Flora Bach
H2 Jonas Dickreuter
H2 Svenja Tan Tjhen
H2 Jürgen Roth
H2 Silvia Teufel-King
H2 Kerstin Justen
H2 Michael Schönenberg
H2 Bernd Seyffer
H2 Michael Hittinger
H2 Rebekka Wiedermann
H2 Jutta Leonhardt-Reichard
H2 Sabrina Schenk
H2 Christina Gesser-Werning
H2 Regine Trostel
H2 Sabine Klever
H2 Reiner Winkler
H2 Katja Doneith
H2 Antonie Matits
H2 Sabine Caroli
H2 Kristiane Göpel
H2 Astrid Gerrards
H2 Katrin Bohlmann-Steeb
H2 Beate Nentwich
H2 Lothar Springmann
H2 Edith Nedelmann
H2 Stefan Balz
H2 Ingeborg Hartung
H2 Wilfried Schucker
H2 Ursula Drachler-Weingärtner
H2 Margarete Leibig
H2 Lea Götz
H2 Lucie Braun
H2 Eckhard Wolscht
H2 Wolfgang Hillermann
H2 Elsbeth Freudenfeld
H2 Michael Steffen Uldrian
H2 Wilfried Schlotter
H2 Elif Çaliskan-Erle
H2 Regina Mattes
H2 Hanne Heilbronner-Walz
H2 Christoph Walker
H2 Heike Fuest
H2 Andrea Wolscht
H2 Melanie Obermayr
H2 Marita Brinkmann
H2 Anna Rilk
H2 Ulrike Held
H2 Martin Leonhardt
H2 Sybille von Bremen-Kühne
H2 Clemens Krause
H2 Peter Graesch
H2 Peter Erwin Schupp
H2 Anke Zeller
H2 Cornelia Kapr
H2 Martina Stohp
H2 Sina Müller
H2 Mechtild Kessler
H2 Monika Gaiser-Maucher
H2 Julia Röhrle
H2 Marlene Jauß
H2 Katharina Keifenheim
H2 Katrin Roth
H2 Ines Franzen
H2 Kristina Ehrlinger
H2 Nadja Oehlmann
H2 Ulrike Detzner-Reiter
H2 Karin Boeckh
H2 Peter Wegner
H2 Uta Grams
H2 Klaus Hesse
H2 Diane Schick
H2 Lena Behmenburg
H2 Anna Gräfin von Moy
H2 Brita Schmid-Jojart
H2 Angelika Maier
H2 Ulrike Lange
H2 Peter Schraivogel
H2 Martin Weber
H2 Anna-Maria Harrer-Lenz
H2 Elisa Franetzki
H2 Marcel Lisson
H2 Katja Hoffmann
H2 Mechthild Böhmer
H2 Joachim Staigle
H2 Maria-Elisabeth Hardt-Svaldi
H2 Jens Leonard
H2 Patrick Hipp
H2 Klaus Kimmerle
H2 Sonja Riedinger
H2 Michael Brunner
H2 Sarah Rippa
H2 Gaby Lippold
H2 Zuzanna Tkaczynska
H2 Liliane Bauer
H2 Ursula Gangl
H2 Susanne Holzapfel-Rossig
H2 Janna Theurer
Some internal links have dynamic parameters. All internal URLs, which are not marked as nofollow, should not contain dynamic parameters.
There are too few (5) internal links on this page.
Every linktext is unique.
None of the anchor texts is too long.
There are too many external links (96) on this page.

Found links on this page

LinkAttributesAnchor text
https://www.praxis-etrich.de/Nofollow External Subdomain URL anchor text
https://www.praxis-etrich.de
https://www.psychotherapie-toe...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-toepperwein.de
https://www.psychoanalyse-assm...Nofollow External Subdomain URL anchor text
https://www.psychoanalyse-assmann.de
https://www.psychotherapie-koo...External Subdomain URL anchor text
https://www.psychotherapie-kooistra.de
https://janz-frisch.de/Nofollow External URL anchor text
https://janz-frisch.de
https://www.psychotherapie-fis...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-fischer.eu
https://www.dr-herold-praxis.de/Nofollow External Subdomain URL anchor text
https://www.dr-herold-praxis.de
https://www.dr-gerd-schaefer.de/Nofollow External Subdomain URL anchor text
https://www.dr-gerd-schaefer.de
https://www.praxis-erne.de/Nofollow External Subdomain URL anchor text
https://www.praxis-erne.de
https://www.psychotherapie-rie...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-riessen.de
http://www.susanneholzapfel.de/Nofollow External Subdomain URL anchor text
http://www.susanneholzapfel.de
https://www.detlef-hielscher.de/Nofollow External Subdomain URL anchor text
https://www.detlef-hielscher.de
https://praxisjung.de/Nofollow External URL anchor text
https://praxisjung.de
https://www.psychotherapiejetz...Nofollow External Subdomain URL anchor text
https://www.psychotherapiejetzt.de
https://praxis-haux.de/Nofollow External URL anchor text
https://praxis-haux.de
http://www.praxis-juliaraabe.de/Nofollow External Subdomain URL anchor text
http://www.praxis-juliaraabe.de
https://www.psychotherapie-sta...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-stark-feger.de
https://www.kunze-psychotherap...Nofollow External Subdomain URL anchor text
https://www.kunze-psychotherapie.de
/www.kjp-kirchentellinsfurt.deNofollow www.kjp-kirchentellinsfurt.de
https://www.stefan-geiselhart-...Nofollow External Subdomain URL anchor text
https://www.stefan-geiselhart-psychotherapie.de
https://www.katrinklingler.de/Nofollow External Subdomain URL anchor text
https://www.katrinklingler.de
http://praxiseder.com/Nofollow External URL anchor text
http://praxiseder.com
https://www.kiviet.de/Nofollow External Subdomain URL anchor text
https://www.kiviet.de
https://www.praxis-boettcher.de/Nofollow External Subdomain URL anchor text
https://www.praxis-boettcher.de
https://psychotherapie-friebe.de/Nofollow External URL anchor text
https://psychotherapie-friebe.de
https://www.verhaltenstherapie...Nofollow External Subdomain URL anchor text
https://www.verhaltenstherapie-tübingen.de
https://www.praxis-ripper.de/Nofollow External Subdomain URL anchor text
https://www.praxis-ripper.de
http://www.daniel-bross.de/Nofollow External Subdomain URL anchor text
http://www.daniel-bross.de
http://www.praxis-sabineschuma...Nofollow External Subdomain URL anchor text
http://www.praxis-sabineschumann.de
https://psychotherapie-am-neck...Nofollow External URL anchor text
https://psychotherapie-am-neckar.de
https://www.psychotherapie-gou...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-goudriaan.de
https://www.nachhaltige-psycho...Nofollow External Subdomain URL anchor text
https://www.nachhaltige-psychotherapie.de
https://roehrle.jimdofree.com/Nofollow External Subdomain URL anchor text
https://roehrle.jimdofree.com
https://psychotherapie-tue.de/Nofollow External URL anchor text
https://psychotherapie-tue.de
https://www.psychotherapie-ulm...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-ulmer.de
https://www.noelke-psychothera...Nofollow External Subdomain URL anchor text
https://www.noelke-psychotherapie.de
https://www.psychotherapie-gun...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-gundel.de
https://www.dr-krist-praxis.de/Nofollow External Subdomain URL anchor text
https://www.dr-krist-praxis.de
https://psychotherapie-praxis-...Nofollow External Subdomain URL anchor text
https://psychotherapie-praxis-mader.jimdofree.com
https://www.drcerff.de/Nofollow External Subdomain URL anchor text
https://www.drcerff.de
https://www.evamariajaeger.de/Nofollow External Subdomain URL anchor text
https://www.evamariajaeger.de
https://www.psychotherapie-noe...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-noell.de
https://psychotherapie-schwaer...Nofollow External URL anchor text
https://psychotherapie-schwaerzler.de
https://www.dr-johannes-hub.de/Nofollow External Subdomain URL anchor text
https://www.dr-johannes-hub.de
https://www.sophia-baar.de/Nofollow External Subdomain URL anchor text
https://www.sophia-baar.de
https://www.mayer-psychotherap...Nofollow External Subdomain URL anchor text
https://www.mayer-psychotherapie.de
https://www.leopold-morbitzer.de/Nofollow External Subdomain URL anchor text
https://www.leopold-morbitzer.de
https://www.psychotherapie-wet...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-wettach.de
https://psychotherapie-zinser.de/Nofollow External URL anchor text
https://psychotherapie-zinser.de
https://www.psychotherapie-in-...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-in-tuebingen.de
https://www.praxis-fuer-ganzhe...Nofollow External Subdomain URL anchor text
https://www.praxis-fuer-ganzheitliche-medizin.de
http://www.dr-smoltczyk.de/Nofollow External Subdomain URL anchor text
http://www.dr-smoltczyk.de
https://www.kossmann-boehm.de/Nofollow External Subdomain URL anchor text
https://www.kossmann-boehm.de
https://gestaltzentrum-tue.de/Nofollow External URL anchor text
https://gestaltzentrum-tue.de
https://www.psychotherapie-pra...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-praxis-tuebingen.de
https://leosuchtmed.de/Nofollow External URL anchor text
https://leosuchtmed.de
https://www.dr-trostel-psychot...Nofollow External Subdomain URL anchor text
https://www.dr-trostel-psychotherapie.de
https://www.praxis-matits.de/Nofollow External Subdomain URL anchor text
https://www.praxis-matits.de
https://www.praxis-nentwich.de/Nofollow External Subdomain URL anchor text
https://www.praxis-nentwich.de
https://www.psychotherapie-ned...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-nedelmann.de
https://www.stefan-balz.de/Nofollow External Subdomain URL anchor text
https://www.stefan-balz.de
https://www.hillermann.eu/Nofollow External Subdomain URL anchor text
https://www.hillermann.eu
https://www.allgemeinmedizin-p...Nofollow External Subdomain URL anchor text
https://www.allgemeinmedizin-psychotherapie-tuebingen.de
https://www.meksmattes.de/Nofollow External Subdomain URL anchor text
https://www.meksmattes.de
https://www.psychotherapie-wol...Nofollow External Subdomain URL anchor text
https://www.psychotherapie-wolscht.de
https://www.praxisobermayr.de/Nofollow External Subdomain URL anchor text
https://www.praxisobermayr.de
https://www.tuebingen-psychoth...Nofollow External Subdomain URL anchor text
https://www.tuebingen-psychotherapie.de
https://psychotherapie-graesch...Nofollow External URL anchor text
https://psychotherapie-graesch.de
http://www.psychotherapie-zell...Nofollow External Subdomain URL anchor text
http://www.psychotherapie-zeller.de
https://www.psychotherapeutin-...Nofollow External Subdomain URL anchor text
https://www.psychotherapeutin-tuebingen.de
https://www.psychotherapiemuel...Nofollow External Subdomain URL anchor text
https://www.psychotherapiemueller.de
https://roehrle.jimdofree.com/Nofollow External Subdomain Text duplicate URL anchor text
https://roehrle.jimdofree.com
https://www.psychotherapiejaus...Nofollow External Subdomain URL anchor text
https://www.psychotherapiejauss.de
https://psychotherapie-keifenh...Nofollow External URL anchor text
https://psychotherapie-keifenheim.de
https://www.praxis-franzen.de/Nofollow External Subdomain URL anchor text
https://www.praxis-franzen.de
https://psychotherapie-oehlman...Nofollow External URL anchor text
https://psychotherapie-oehlmann.de
http://www.dr-detzner-reiter.de/Nofollow External Subdomain URL anchor text
http://www.dr-detzner-reiter.de
https://www.karin-boeckh.de/Nofollow External Subdomain URL anchor text
https://www.karin-boeckh.de
https://www.drpeterwegner.de/Nofollow External Subdomain URL anchor text
https://www.drpeterwegner.de
https://www.grams-psychotherap...Nofollow External Subdomain URL anchor text
https://www.grams-psychotherapie.de
https://psychotherapiepraxis-t...Nofollow External URL anchor text
https://psychotherapiepraxis-tuebingen.de
https://schick-psychosomatik.de/Nofollow External URL anchor text
https://schick-psychosomatik.de
http://www.praxis-behmenburg.de/Nofollow External Subdomain URL anchor text
http://www.praxis-behmenburg.de
http://kjp-rottenburg.de/Nofollow External URL anchor text
http://kjp-rottenburg.de
https://psychotherapie-am-neck...Nofollow External Text duplicate URL anchor text
https://psychotherapie-am-neckar.de
http://www.m-lisson.de/Nofollow External Subdomain URL anchor text
http://www.m-lisson.de
https://www.hoffmann-tuebingen...Nofollow External Subdomain URL anchor text
https://www.hoffmann-tuebingen.de
https://praxis-boehmer.de/Nofollow External URL anchor text
https://praxis-boehmer.de
https://www.psychotherapeut-tu...Nofollow External Subdomain URL anchor text
https://www.psychotherapeut-tuebingen.de
https://www.jens-leonard.de/Nofollow External Subdomain URL anchor text
https://www.jens-leonard.de
https://psychotherapiepraxis-h...Nofollow External URL anchor text
https://psychotherapiepraxis-hipp.de
https://www.pt-brunner.de/Nofollow External Subdomain URL anchor text
https://www.pt-brunner.de
https://psychotherapiepraxis-t...Nofollow External Text duplicate URL anchor text
https://psychotherapiepraxis-tuebingen.de
https://www.psychologin-therap...Nofollow External Subdomain URL anchor text
https://www.psychologin-therapeutin.de
https://www.tkaczynska.de/Nofollow External Subdomain URL anchor text
https://www.tkaczynska.de
http://www.psychotherapie-gang...Nofollow External Subdomain URL anchor text
http://www.psychotherapie-gangl.de
http://www.susanneholzapfel.de/Nofollow External Subdomain Text duplicate URL anchor text
http://www.susanneholzapfel.de
/kontakt?anliegen=eintragenPsychotherapeut eintragen
/kontakt?anliegen=berichtigenEintrag berichtigen
/kontakt?anliegen=loeschenEintrag löschen
/datenschutzDatenschutz
/impressumImpressum

Server configuration

HTTP redirects
(Critically important)
This page redirects to "https://www.psychotherapeuten-liste-tuebingen.de/"
HTTP header
(Important)
No X-Powered HTTP header is sent.
The web server transmits the web page (HTML) in compressed form.
Performance
(Somewhat important)
The page response time is excellent with 0.26 seconds.
The file size of the HTML document is fine (162 kB).

HTTP Response Header

NameValue
content-typetext/html; charset=UTF-8
x-ws-ratelimit-limit1000
x-ws-ratelimit-remaining998
dateWed, 13 Aug 2025 03:24:10 GMT
serverApache
content-encodinggzip
statuscode200
http_versionHTTP/2

External factors

We didn't find any backlinks to this page.

Links from Wikipedia

No links from Wikipedia were found.

Robots.txt

User-agent: *
Disallow:

Similar sites

Search preview

www.psychotherapeuten-liste-tuebingen.de
Psychotherapeuten-Liste Tübingen
Liste von Psychotherapeuten und Psychotherapeutinnen in Tübingen

Most important keywords

Following keywords were found. You can check the keyword optimization of this page for each keyword.

KeywordResultRecheck
Tübingen85%Check
Psychotherapeuten85%Check
Psychotherapeuten-Liste Tübingen79%Check
Psychotherapeuten-Liste73%Check
72072 Tübingen60%Check
72074 Tübingen60%Check
72070 Tübingen60%Check
72076 Tübingen60%Check
Landkreis Tübingen60%Check
15 72072 Tübingen51%Check
Show more keywords and terms

Automatically check psychotherapeuten-liste-tuebingen.de including all subpages at once!

Try for free
Guaranteed free of charge during trial period.

Cookie Policy

We use cookies to make our site work and also for analytics and advertising purposes. You can enable or disable optional cookies as desired. See the following links for more information.

Contact | Privacy

We need these so the site can function properly

So we can better understand how visitors use our website

So we can serve you tailored ads and promotions