Many SEO analysis tools exist. Here, we’ll discuss Google’s Lighthouse tool which can help you with search engine optimization (SEO).
It provides access to Google’s scores for 4 criteria (out of 100), as well as opportunities for improvement on each of these criteria. Allowing you to optimize your SEO.
How does Google's Lighthouse work?
This tool works as a browser extension. Once installed, simply pin it to your browser bar, as shown here circled in red:
Then go to the page you want to analyze, and press the circled lighthouse icon (above).
A message like this will appear:
All that’s left to do is click on “Generate report”, and you’ll be taken to a new tab that looks just like this one:
Links to install on your browser:
- Google Chrome: install Lighthouse on Google Chrome
- Firefox: install Lighthouse on Mozilla Firefox
Who can use Lighthouse?
Lighthouse is a comprehensive and highly detailed tool. It gives access to metrics that only connoisseurs of website development can understand. More generally, the tool’s language is quite advanced. Nonetheless, a web designer or a marketing manager with a “knack for everything” can understand some of the remarks made by the tool.
This is how it works:
- It displays the score out of 100 for the 4 scores
- Metrics and criteria for improvement
- Those already upgraded.
Lighthouse is the quick auditing tool you need when you can’t afford full-time consultants for your company.
The different scores for optimizing your search engine optimization
The performance score is weighted by several criteria evaluated by Google:
- First Contentful Paint (10%)
The “First Contentful Paint” (FCP) calculates the time taken for the very first pixels of content to appear when loading a web page. In this case, it should be as low as possible.
- Speed index ((SI) 10%)
The “Speed index” calculates the speed of appearance of a page’s overall content.
Among the proposed improvements is the reduction of unused Javascript.
- Largest Contentful Paint (25%)
The “Largest Contentful Paint” (LCP) calculates the appearance time of the largest content item on a web page (image, video, block of text, etc.).
Among the proposed improvements is the use of the .WEBP extension for images used on a page, instead of the traditional .PNG, .JPG and .JPEG. This makes the site lighter.
- Time to Interactive (10%)
Time to Interactive (TTI) is the latency before the content displayed becomes interactive. In other words, accessible and approachable by the user.
- Total Blocking Time (30%)
Measured in milliseconds, this so-called “blocking time” is the time interval between the very first content pixel (FCP) and the waiting time for 1st interactivity (TTI).
- Cumulative Layout Shift (15%)
When a page is loaded:
- fonts should enlarge during display,
- images must be repositioned,
- buttons appear,
- or down links because the text above has moved.
The Cumulative Layout Shift (CLS) calculates the number of times these events can occur on a page.
As the name suggests, this score indicates how accessible the site is to the greatest number. There’s no doubt about the number of blockages users may experience. The accessibility that Google evaluates is based on 4 criteria:
The obstacles and bad experiences associated with these 4 points when visiting a website are mostly due to disability. But also from external factors on able-bodied people, for example: daylight which can be annoying, a grabbed hand, etc.
The vision
People with visual impairments use:
- voice synthesis,
- themes with a strong contrast,
- or sometimes even a screen reader.
In other cases, the use of Braille is necessary to understand an Internet page. In particular, it enables actions to be performed, pages to be navigated or content to be read.
There are several ways to improve:
→ Play on the color contrast between the background and the writing.
→ Every piece of content on a page should have a unique ID (identifier). Images with an <alt> attribute, a <title> for each document, etc.
→ High zoom power, etc.
Motor skills / Dexterity
People with motor/dexterity impairments may have difficulty using computer mice, touch screens and so on. To help themselves, they use special keyboards, voice access devices to command an action, etc.
For this reason, several criteria must be respected, including the legibility of action buttons/links (CTA = Call To Action).
→ They should have a legible title where the action is clear and well explained. → Icons without text or context can hinder voice commands, or simple machine reading of the image. But also lose the reader from understanding the site.
Audition
For hearing-impaired users, it’s important that audio elements are audio-describable. That is, with written captions and transcriptions.
Cognitive
Cognitive impairments include many different and more general disorders: dyslexia, autism, ADHD, etc. Users with these disorders have very little tolerance for flashes of light, sudden movements between page contents, bright colors, etc. They therefore use specific contrasts and themes to prevent, among other things, pain and discomfort. They therefore use specific contrasts and themes to prevent headaches, or sometimes seizures.
Your site must be easy to read despite these changes in contrast or theme, sometimes dark or in black and white.
This score evaluates the respect of several good practices to keep your site in good health. More specifically, the health of its code. They are more general than for the other categories.
→ Use of HTTPS(HyperText Transfer Protocol Secure) Internet protocol
→ The UX (User Exeperience) of geolocation permissions or simple notification.
→ Respecting image ratios in particular to be responsive (= adapted to mobiles, tablets, and other devices with different formats). And always respect a good image resolution.
This SEO score ensures that your website is optimized to rank well on search engines like Google. To achieve this, there are a number of criteria to be met, such as:
→ One meta description per page of your site. A must!
→ A respected “href” attribute for each link so that they are all usable by Google.
→ A “hreflang” attribute appropriate to the correct site language used when reading it. Even for multilingual sites.
→ Sufficiently legible font size. This criterion also applies to the accessibility score.
→ The same goes for interactive elements, which need to be large enough to be used by a large number of people. The minimum recommended size is 48x48px (px = pixel). It’s also important that there’s as much space as possible around these elements so as not to mislead users into clicking elsewhere.
Finally, all these scores and evaluation criteria used by Google are based on the logic of user experience.
When we visit a website, we appreciate the speed at which content appears, the ease with which it can be read, the right content sizes, the clarity of the content, etc.
