OSX El Capitan 10.11.6
Does Apple still support this version? If not, what is the best option? My computer was purchased in 2010.
iMac, OS X 10.11
Question marked as
El Capitan, Sierra, High Sierra, Mojave are no longer getting any Security updates.
Catalina will probably be ending Security Updates later this year
The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.
With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install. For Best results use Safari to commence the download as Others may not work.
Safari will open a redirect and open the Apple Store where the download can commence.
macOS Catalina 10.15 hardware requirements
macOS Mojave 10.14 hardware requirements
macOS High Sierra 10.13 hardware requirements This version is probably the last version this computer Qualifies to run
macOS Sierra 10.12 hardware requirements
Make Time Machine Backup is very useful and can be used to Revert to Previous Working macOS