TL;DR: The pandemic has apparently been good to Google's Chrome OS. Last year it increased its user base by 4.4 percent, surpassing Apple's macOS and taking second place in OS market share. Windows lost nearly five percent of the market, but unsurprisingly still commands the PC landscape.
According to numbers from market research firm IDC, Chrome OS overtook macOS for the first time in 2020 in user install base. For decades, Windows has had a stranglehold on the PC market, and that has not changed. The contest has historically been between macOS, Linux, and, more recently, Chrome OS.
Macs have held second place in global market share for quite a while. However, GeekWire reports that in 2020, Chrome OS slipped ahead, holding 10.8 percent of the market. Chromebooks have beat out Macs on a quarterly basis in the past, but this is the first time year-end numbers saw the Google-owned OS growth exceed Apple's. The increase is made more significant considering Mac market share rose from 6.7 percent in 2019 to 7.5 percent in 2020.
Although it is still nowhere close to Windows' install base, Chrome's growth from 6.4 percent to 10.8 took a small bite out of Microsoft's hold as its slice of the pie slid from 85.4 percent in 2019 to 80.5 percent last year. However, it is worth noting that 2020 was far from typical as far as PC sales go. General PC sales were up thanks to the many who were forced to work from home. But educational tools in the form of Chromebooks may have superseded home and business use in 2020.
Many schools took advantage of deep discounts offered to educators for Chromebooks. Most districts increased their inventories of inexpensive Chromebooks to help loan equipment to children who might not have their own computers, so last year's numbers might be somewhat skewed. How long this trend will continue remains to be seen, but as of this writing, there are still many students enrolled in distance learning models. It may be some time before the demand shifts to more normal levels.