Understanding the browser's market share
Before getting into all the emulation features Puppeteer provides, I would like to discuss how the browser's market share looks these days. I believe that will give you a clear picture of the importance of testing and emulating different scenarios.
The browser's popularity over the years
We have lived through lots of changes over the past 25 years. Browsers have been dramatically adopted and discarded. Let's take a look at this table made by Nick Routley in his post Internet Browser Market Share (1996–2019) (https://www.visualcapitalist.com/internet-browser-market-share/):
Although I used Netscape Navigator, I wasn't there at its peak back in 1995. But I remember the days when the only browser that mattered was Internet Explorer.
The community was living through browser fatigue back in 2008, when Google Chrome was launched, causing a massive number of users to move to Google...