On Windows, you can check the features of your CPU using a tool like CPU-Z.
On the web, you can look up your CPU on Intel ARK and see its details. This is not recommended, since ARK does not show all the flags or features of a CPU.
On Linux, I like to look at the
flags section of
/proc/cpuinfo. To see what feature maps to each flag, see the
arch/x86/include/asm/cpufeature.h in the Linux source code. The flags will all have a prefix of
X86_FEATURE_ and the comment that follows describes the feature.