Explainthatstuff.com - SEO Checker

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Overview of the SEO Check
Meta information
85% 
Page quality
95% 
Page structure
58% 
Link structure
83% 
Server
87% 
External factors
100% 
SEO Score
Response time
1.84 s
File size
53.40 kB
Words
1941
Media files
46
Number of links
81 internal / 17 external

Task list of SEO Improvements

Meta specifications

Title
(Critically important)
Explain that Stuff
The page title is too short. (152 pixels of 580 max pixel length) Optimize title
There are no duplicate words in the title
Meta description
(Critically important)
A collection of FREE, easy-to-understand science, technology, and how-it-works articles for the whole family!
The length of the meta description is perfect. (668 pixels out of 1000 max pixel length)
Crawlability
(Critically important)
There are no problems in accessing the website.
Canonical URL
(Important)
https://www.explainthatstuff.com/
There is a valid canonical link specified.
Language
(Somewhat important)
Language detected in text: en
Server location: United States of America
The language is not specified in the HTML markup.
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 is no subdomain.
The domain length is good.
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)
The favicon is linked correctly.

Meta tags

NameValue
viewportwidth=device-width, initial-scale=1.0
ROBOTSNOODP
descriptionA collection of FREE, easy-to-understand science, technology, and how-it-works articles for the whole family!
alexaVerifyIDzJwPnVZprXRC-PX4afd9jAZ6IV8
verify-v1Lrg/eKaJEvWUlgZIpFJ8TzpF0On2WbpHocUuNI1xp/Q=
google-site-verificationrHVKo-E_tpyTAHAW2_XABOTBH9iSN7oRdbCxco5kIn4
theme-color#1D3557
robotsmax-image-preview:large
article:publisherhttps://www.facebook.com/explainthatstuff
article:authorhttps://www.chriswoodford.com/
article:published_time2006-04-23
article:modified_time2025-06-01
fb:app_id1678539732394615
og:urlhttp://www.explainthatstuff.com/
og:typewebsite
og:site_nameExplain that Stuff
og:titleExplain that stuff! Science and technology made simple
og:descriptionWe make science and technology easy to understand.
og:imagehttps://cdn4.explainthatstuff.com/optical-mouse-light-guide-large-og.jpg
Content-typetext/html;charset=UTF-8
PICS-Label(PICS-1.1 "http://www.classify.org/safesurf/" L gen true for "https://www.explainthatstuff.com/" r (SS~~000 1))

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Page quality

Content
(Critically important)
These Typos were found:
  • millenia => millennia
This page contains 1941 words. That's ok.
43.9% of the text are stop words.
Keywords used in the page title are also used in the page content. That's good!
Words from the H1 heading are used in the page content.
The page contains a listing, which indicates a good text layout.
48 paragraphs were found on this page.
The text content is perfect.
No placeholders texts or images were found.
There are no duplicates on the site.
The average number of words per sentence of 15.69 words is good.
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=1.0" is provided.
Bold and strong tags
(Somewhat important)
The usage of strong and bold tags is perfect. We recommend the use of up to 39 tags for this page.
Image SEO
(Somewhat important)
Alt text (alternative text) is correctly used on all found images.
Social Networks
(Nice to have)
This page is optimized perfectly for social networks.
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

URLAlt attributeTitle
...plainthatstuff.com/ets-wide-logo-rgb.pngExplain that Stuff
cdn4.explainthatstuff.com/ccd-chip4.jpgCCD chip from a webcam.
....explainthatstuff.com/turbine-model3.jpgModel of a steam turbine at Think Tank science museum, Birmingham, England.
...om/how-ground-source-heat-pump-works.pngHow a ground-source heat pump uses a heat exchanger.
...stuff.com/laser-alignment-experiment.jpgLaser align experiment showing red, green, and yellow laser beams intersecting in a glass prism.
...uff.com/geoengineering-earth-spanner.jpgGeoengineering conceptual illustration: Earth inside a spanner.
...hatstuff.com/nasa-airs-warming-thumb.jpgConceptual artwork of a warming world.
...uff.com/everyday-materials-selection.jpgAssortment of everyday materials.
...tuff.com/rocket-engine-launch-flames.jpgSpace rocket engine flames.
...tstuff.com/quantum-computing-concept.pngConceptual artwork of a quantum computer.
...tuff.com/ai-concept-dummy-chip-thumb.jpgConcept of artificial intelligence: an AI dummy superimposed on a green circuit board.
.../nokia-lithium-ion-cellphone-battery.jpgBlack Nokia cellphone battery.
...inthatstuff.com/how-hybrid-car-works.pngHow a hybrid car works.
...tuff.com/ai-concept-dummy-chip-thumb.jpgConcept of artificial intelligence: an AI dummy superimposed on a green circuit board.
...uff.com/earth-gravity-stronger-poles.pngThe force of gravity is slightly greater at the equator than at the poles airplane.
...om/supersonic-schlieren-orange-thumb.jpgOrange Schlieren photograph of two supersonic jets flying upward
...hatstuff.com/crane-pulleys-red-thumb.jpgGiant pulley wheels in a large crane
...com/aristotle-freeze-highsmith-thumb.jpgAristotle pictured at the National Academy of Sciences, Washington, D.C.
...tuff.com/computer-software-dvd-thumb.jpgBlack laptop computer loading software from an open red DVD
....com/silverback-gorilla-bamboo-thumb.jpgSilverback gorilla eating bamboo.
...m/nasa-blue-organisms-lighting-thumb.jpgExperiment exposing organisms to blue excitation lighting
...dn4.explainthatstuff.com/radio-thumb.jpgGray plastic Hitachi transistor radio
...tuff.com/crop-spraying-tractor-thumb.jpgPhoto of red tractor spraying crops with pesticide or insecticide.
...thatstuff.com/electricity-plug-thumb.jpgWhite electricity plug with two pins.
...m/atomic-force-microscope-tips-thumb.jpgThe tips of the atomic force microscope (AFM) probe used on the NASA Mars Phoenix Lander.
...xplainthatstuff.com/magnet-big-thumb.jpgHorseshoe magnet
...hatstuff.com/rackandpiniongear-thumb.jpgRack and pinion gear made with an erector set
...explainthatstuff.com/batteries-thumb.jpgA dry cell Ever Ready battery.
...uff.com/electric-motor-closeup-thumb.jpgA large electric motor from an electric lawn mower
...hatstuff.com/nasa-airs-warming-thumb.jpgConceptual artwork of a warming world.
....com/cloud-computing-composite-thumb.jpgComposite photo showing NASA supercomputer floating in a cloud
...ainthatstuff.com/digitalcamera-thumb.jpgBasic digital camera
...grated-circuit-microcontroller-thumb.jpgTypical microcontroller microchip in a dual-in-line package.
...atstuff.com/digital-multimeter-thumb.jpgA digital voltmeter standing with red and black probes attached, wired into a circuit to test a simple 1.5-volt battery.
...atstuff.com/bluegasflameenergy-thumb.jpgBlue flame of a natural gas cooker.
...tstuff.com/spring-arch-fingers-thumb.jpgSmall steel spring flexed in a curve between two fingers.
...xplainthatstuff.com/organicbox-thumb.jpgOrganic vegetable box
....com/sony-bravia-flatscreen-tv-thumb.jpgSony Bravia flatscreen TV
....com/solar-control-low-e-glass-thumb.jpgBlue, self-cleaning, heat-reflecting glass keeps a conservatory cool.
...l-framed-building-construction-thumb.jpgBlue, self-cleaning, heat-reflecting glass keeps a conservatory cool.
...soap-bubble-color-interference-thumb.jpgA rainbow-spectrum of colors on the surface of a soap bubble produced by thin-film interference.
...thatstuff.com/hydraulicdigger2-thumb.jpgClose-up of hydraulic rams on a digger
...tstuff.com/c17globemasterplane-thumb.jpgFront view of huge USAF C-17 globemaster plane waiting on a runway
...tstuff.com/optical-mouse-light-guide.jpgOptical mouse circuit board with red LED light shining through light guide.
...plainthatstuff.com/ets-wide-logo-rgb.pngExplain that Stuff

Page structure

H1 heading
(Critically important)
The FREE science and technology book
The H1 heading is perfect.
Headings
(Important)
Some headings occur twice on the page.
There are 53 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 The FREE science and technology book
H2 Hard stuff... made simple!
H2 How to use this site
H2 What's hot in June 2025?
H2 What's new?
H2 Most popular
H2 What else is on our site?
H2 Who uses this site?
H2 Follow us on your favorite sites!
H2 Tell your friends
H2 Privacy and cookies
H2 Can't find what you want? Search our site below↓
H2 More to explore on our website...
H3 Heat pumps
H3 Lasers
H3 Geoengineering
H3 Climate change
H3 Materials
H3 Space rockets
H3 Quantum computing
H3 Artificial intelligence
H3 Lithium-ion batteries
H3 Electric cars
H3 Artificial intelligence Duplicate text
H3 Gravity
H3 History of flight
H3 Cranes
H3 History of electricity
H3 Software
H3 Great psychology experiments
H3 What is science—and why does it matter?
H3 History of communication
H3 Water pollution
H3 Electricity
H3 Nanotechnology
H3 Magnetism
H3 Gears
H3 Batteries
H3 Electric motors
H3 Global warming
H3 Cloud computing
H3 Communications
H3 Computers
H3 Electricity and electronics
H3 Energy
H3 Engineering
H3 Environment
H3 Gadgets
H3 Home life
H3 Materials Duplicate text
H3 Science
H3 Tools, instruments, and measurement
H3 Transportation
Some anchor texts are used more than once.
The number of internal links is ok.
None of the anchor texts is too long.
All internal links are not using dynamic parameters.
There are 17 external links on this page.

Found links on this page

LinkAttributesAnchor text
https://www.explainthatstuff.com/IMG-ALT Explain that Stuff
/searchmob.htmlA-TITLE Site search
https://www.explainthatstuff.com/Anchor A-TITLE Site navigation
https://www.explainthatstuff.com/Home
/azindex.htmlA-Z index
/random.phpRandom article
/timeline.htmlTimeline
/teaching-guide.htmlTeaching guide
/aboutus.htmlAbout us
/privacy.htmlPrivacy & cookies
https://api.whatsapp.com/send?...New window External Subdomain A-TITLE Share this on WhatsApp
https://www.facebook.com/share...New window External Subdomain A-TITLE Share this on Facebook
/chris-woodford.htmlChris Woodford
/teaching-guide.htmlcurriculum learning
/azindex.htmlText duplicate A-Z index
/timeline.htmlText duplicate Timeline
/random.phpRandom
https://www.explainthatstuff.com/Anchor Search
/teaching-guide.htmlText duplicate Teaching guide
/heatpumps.htmlHeat pumps
https://www.bbc.co.uk/news/art...New window External Subdomain News story
/lasers.htmlLasers
https://www.sciencenews.org/ar...New window External Subdomain Text duplicate News story
/geoengineering.htmlGeoengineering
https://www.sciencenews.org/ar...New window External Subdomain Text duplicate News story
/globalwarmingforkids.htmlClimate change
https://wmo.int/news/media-cen...New window External Text duplicate News story
/materials-science.htmlMaterials
https://www.nytimes.com/2024/1...New window External Subdomain Text duplicate News story
/spacerockets.htmlSpace rockets
https://www.bbc.co.uk/news/vid...New window External Subdomain Text duplicate News story
/quantum-computing.htmlQuantum computing
https://www.bbc.co.uk/news/art...New window External Subdomain Text duplicate News story
/artificial-intelligence.htmlArtificial intelligence
https://www.nytimes.com/2024/1...New window External Subdomain Text duplicate News story
/how-lithium-ion-batteries-wor...Lithium-ion batteries
https://www.nytimes.com/2024/0...New window External Subdomain Text duplicate News story
/electriccars.htmlElectric cars
/artificial-intelligence.htmlText duplicate Artificial intelligence
/gravity.htmlGravity
/history-of-flight.htmlHistory of flight
/cranes.htmlCranes
/history-of-electricity.htmlHistory of electricity
/software.htmlSoftware
/great-psychology-experiments....Great psychology experiments
/what-is-science.htmlWhat is science—and why does it matter?
/history-of-communication.htmlHistory of communication
/waterpollution.htmlWater pollution
/electricity.htmlElectricity
/nanotechnologyforkids.htmlNanotechnology
/magnetism.htmlMagnetism
/gears.htmlGears
/batteries.htmlBatteries
/electricmotors.htmlElectric motors
/globalwarmingforkids.htmlGlobal warming
/cloud-computing-introduction....Cloud computing
/articles_communications.htmlCommunications
/articles_computers.htmlComputers
/articles_electricity.htmlElectricity and electronics
/articles_energy.htmlEnergy
/articles_engineering.htmlEngineering
/articles_environment.htmlEnvironment
/articles_gadgets.htmlGadgets
/articles_homelife.htmlHome life
/articles_materials.htmlText duplicate Materials
/articles_science.htmlScience
/articles_tools.htmlTools, instruments, and measurement
/articles_transportation.htmlTransportation
https://www.google.com/search?...New window External Subdomain dozens of books
https://scholar.google.com/sch...New window External Subdomain over 2000 academic papers and patents
/feedback.phpfeedback forms
https://www.facebook.com/expla...New window External Subdomain our friendly Facebook page
http://www.flickr.com/explaint...New window External Subdomain Flickr
https://www.pinterest.co.uk/ex...New window External Subdomain Pinterest
https://podcast.explainthatstu...New window External Subdomain subscribing to our podcast feed
/donotsell.html"Do Not Sell My Personal Information"
/privacy.htmlprivacy policy
/copyright-and-legal-notices.htmlFull copyright notice and terms of use
/articles_communications.htmlText duplicate Communications
/articles_computers.htmlText duplicate Computers
/articles_electricity.htmlElectricity & electronics
/articles_energy.htmlText duplicate Energy
/articles_engineering.htmlText duplicate Engineering
/articles_environment.htmlText duplicate Environment
/articles_gadgets.htmlText duplicate Gadgets
/articles_homelife.htmlText duplicate Home life
/articles_materials.htmlText duplicate Materials
/articles_science.htmlText duplicate Science
/articles_tools.htmlTools & instruments
/articles_transportation.htmlText duplicate Transportation
/azindex.htmlText duplicate A-Z index
/feedback.phpSend feedback
/random.phpText duplicate Random article
/timeline.htmlText duplicate Timeline
/teaching-guide.htmlText duplicate Teaching guide
/aboutus.htmlText duplicate About us
/privacy.htmlText duplicate Privacy & cookies
https://www.explainthatstuff.com/Anchor Back to top

Server configuration

HTTP redirects
(Critically important)
This page redirects to "https://www.explainthatstuff.com/"
HTTP header
(Important)
The X-powered header is sent within the response header. (unnecessary)
The web server transmits the web page (HTML) in compressed form.
Performance
(Somewhat important)
The page response time is very slow (1.84 seconds). The response time should be less than 0.4 seconds. Slow websites are bad for search engine bots and also result in bad user experience.
The file size of the HTML document is fine (53 kB).

HTTP Response Header

NameValue
dateSun, 27 Jul 2025 21:14:49 GMT
serverApache
x-powered-byPHP/8.4.10
strict-transport-securitymax-age=15552000; includeSubDomains
x-frame-optionsSAMEORIGIN
varyAccept-Encoding,User-Agent
content-encodinggzip
cache-controlmax-age=259200, must-revalidate
content-length17072
content-typetext/html; charset=UTF-8
statuscode200
http_versionHTTP/2

External factors

This page is referenced by wikipedia.
This website has excellent links from other websites.
This page has backlinks from 115 referring domains.
This page has 280 backlinks.
This page has backlinks from 104 different ip addresses.

Links from Wikipedia

You can find more links using Wikipedia search

Robots.txt

User-agent: *
Allow: /*.js
Disallow: /audio/
Disallow: /cgi-bin/
Disallow: /includes/
Disallow: /random.php
Disallow: /Mobile_Detect.php
Disallow: /mobiletop.html
Disallow: /mobilemid.html
Disallow: /desktoptop.html
Disallow: /desktopmid.html
Disallow: /mobiletop-noad.html
Disallow: /mobilemid-noad.html
Disallow: /desktoptop-noad.html
Disallow: /desktopmid-noad.html
Disallow: /searchjava.html
Disallow: /bottomsearch.html
Disallow: /mobilebotad.html
Disallow: /desktopbotad.html
Disallow: /desktopbotad2.html
Disallow: /facebook-desktop.html
Disallow: /facebook-mobile.html
Disallow: /mobilemid2.html
Disallow: /mobilebotad2.html
Disallow: /desktoptop2.html
Disallow: /desktopmid2.html
Disallow: /analytics.html
Disallow: /mobile-search.html


User-agent: AhrefsBot
Disallow: /

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www.explainthatstuff.com
Explain that Stuff
A collection of FREE, easy-to-understand science, technology, and how-it-works articles for the whole family!

Most important keywords

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

KeywordResultRecheck
science68%Check
technology66%Check
science technology66%Check
stuff65%Check
FREE63%Check
Explain61%Check
Science News52%Check
Technology News52%Check
ll find52%Check
site51%Check
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