What is GTmetrix? – Definition
GTmetrix is one of the free tools used to get detailed reports on website performance. It analyzes the website speed using Google Page Speed and YSlow guidelines. GTmetrix checks that the front-end of the entire site is consistent with the recommended practices.
A good PageSpeed/YSlow score means that the page is optimized for the fastest possible rendering by the web browser.
Importance for SEO
GTmetrix plays an important role in SEO as Google uses the Page Speed result in its ranking algorithm. Correct website speed makes indexing easier for search engines and increases the level of user satisfaction. It is worth keeping this in mind when optimizing your website.