OptiFine

OptiFog
OptiFine started as a small mod called OptiFog firstly released in Beta 1.4. Mod was orignally about pushing the fog away but other features like [FPS Boost], [Occlussion Culling] (hidden geometry removal), texture mipmaping or chunk loading optimizations were in the first version.

In the next version, OptiFog got compatibility with Optimine, ModLoader and in some ways with MCPatcher. It added Smooth FPS, Brightness and VSync (frame limit). In Beta 1.6.6, mod Lag Spikes of Death was added to OptiFine, and support for HD textures and MCPatcher wasn't needed in a mod, added Better Grass, configurable Smooth Lighting, fast Debug Info, clouds height, and fixed light levels. OptiFog 1.7.2_HD_C was the last version of OptiFog and added support for HD fonts.

OptiFine in Late Beta
OptiFine for Beta 1.7.3 was the first version of OptiFine itself, made by sp614x itself with code from OptiMine and additions like Zoom and SmoothInput. But versions for OptiMine and OptiFog were released although they did not add new things. The last version for Optimine was for Beta 1.8.1..

OptiFine
Within the last Optimine version was released, OptiFine got really big popularity and it became a daily-used mod. When OptiFine 1.0 released, and features Smart texture pack switching, faster mipmaps, animated terrain, and items and customizes were added, OptiFine was already known as the most used mod in Minecraft. 1.1 was not so big update, but Random Mobs, option Swamp Colors, custom HD Font widths, far arrow render still helped grew up the popularity of OptiFine.

In 1.2.5, OptiFine Ultra wasthat it doesn't need Forge or ModLoader. Otherwise, 1.2.5 OptiFine added custom lighting, added fog and sky colors for the Nether/End, variable render distance, added sun, moon, and stars in Tiny and Short render distance and fixed some bugs. In 1.3.2, only fixes occur.

Before 1.7.10, there were 6 versions in development- Standard, Smooth, Multi-Core, AA (anisotropic filtering, antialiasing), Light, and Ultra. After 1.7.10, only Ultra was in development, so it was compatible only with Forge and HD Textures (with HD Fonts). In 1.8.8, so requested shaders were added from ShadersMod. 1.13.2 added CEM models for horse, dolphin and drowned and 1.14.3 restored void rendering, needed by shaders sky.

OptiFine today
The latest version is for 1.17.1.x. OptiFine is still one of the most used utilities in Minecraft. Although there were exploits like rendering glitch in Beta 1.7.3 which made the game unplayable probably 5 million blocks from spawn or chunk exploits in Java Edition 1.12, players still liked this mod and they still like it today.

Popularity
OptiFine was really popular, especially with many things it included. For oldest hardware, it included many options to have more FPS in the game. On other side - The newest one, it had many features, which could make it more beautiful - HD Textures support, Shaders, long distance render.

Trivia

 * Forge needs a special mod designed for OptiFine - OptiForge
 * Fabric also needs a special mod designed for OptiFine - OptiFabric