You have developed your webpage. Knowingly / unknowlingly you have added various javascripts, several images. You do not know if the webpage is SEO friendly. Your customer suddenly throws a new requirement at you -> web App needs to be optimized so it can run on a 3g network without any hiccups & wants to audit your web pages.

No need to sweat !!! Lighthouse is an open source tool that can be run from your chrome browser to audit any webpages for performance, accessibility, SEO friendliness & web best practices.