Dictionary
Lighthouse
A free tool built into Chrome DevTools that audits performance, accessibility, best practices, and SEO at once.
In more detail
What It Means
Lighthouse is a free auditing tool built directly into Chrome DevTools that scores a page on performance, accessibility, best practices, and SEO in one report. It is usually the fastest way to find out what is wrong with a page before reaching for anything else.
See it in context on the homepage: Performance (And How to Prove It).