AVX or Advanced Vector Extensions are additions to the x86 instruction set architecture, which pertain to Intel and AMD CPU's that use x86 architecture.
Put simply, the additional instruction set allow compatible processors to perform more demanding functions when used with compatible software. AVX is a hardware dependent feature and software or firmware updates cannot introduce the feature if your CPU does not support it.
What does that mean for Serato software?
Serato DJ Pro, Serato DJ Lite (3.0 or higher) & Serato Studio (2.0 or higher) all require a CPU that supports the AVX instruction set, and will not install if your computer contains an older CPU without this feature.
NOTE: Above and subsequent mentions of 'AVX' refer to the original specification, rather than the AVX2 or AVX-512 iterations, which are not currently required for Serato software.
How can I check my CPU supports AVX?
Trying to download and install Serato DJ Pro, Lite (3.0 or higher) or Serato Studio (2.0 or higher) is actually the easiest way to check if your computer hardware supports AVX, and will result in a failed installation advising "Serato DJ requires a CPU which supports the AVX instruction set" or "Serato Studio requires a CPU which supports the AVX instruction set" if your computer does not meet the requirement.
If you're looking to purchase a second-hand computer that you don't have access to currently (and thus can't try the respective installer on), and want to know if it supports AVX - a quick answer is that most supported Intel Core i-series CPU's with the Sandy Bridge micro-architecture from 2011 onwards, and all supported AMD Ryzen CPU's support AVX.
If you're having trouble identifying if your CPU supports AVX please feel free to open a help request with our Support team, who can assist, here.