What does Streaming SIMD Instructions (SSE) mean?

The field of IT has more acronyms than the Earth has blades of grass. One of these is SSE (short for Streaming single instruction, multiple data instructions extension. Boy is that a mouthful.) Thankfully, SSE isn't as intimidating as it sounds. But in order to understand it, we must understand what instructions are. Instructions simply are a part of the computer that tells the CPU what to do (divide two numbers, store this information in RAM, etc).

SSE was introduced on the P3 (Pentium III) in order to speed up tasks CPUs struggled with, like DVD playback. SSE allowed a single instruction to handle more than one piece of data at a time, hence single instruction, multiple data without affecting basic CPU instructions. Currently, SSE has 5 generations, expressed as such: SSE, SSE2 etc.. Below is a basic list of improvements each generation brought

SSE2 - Similar to SSE but added ability to deal with double precision floating point numbers
SSE3 - Improved on SSE2 but improved process thread management and 3D operations
SSE4 - Improved text manipulation and media encoding. Comes in a few different flavours, 4.1, 4.2 and 4a (AMD)
SSE5 - Introduced by AMD on their Bulldozer CPUs in 2011. Improved performance for single threads and AES (advanced encryption standard) encryption.