The Tekkit mod pack is a large collection of Minecraft mods created by the Technic team to enhance the game experience. The current available versions are Tekkit Classic, Tekkit Lite and Tekkit.
The original Tekkit Classic is designed to run on Minecraft version 1.2.5. The pack features 29 mods, including Railcraft, Ender Storage and Inventory Tweaks. In Double Up Gaming's "Top 10 Minecraft Modpacks 2015," Tekkit Classic ranked #1.
Tekkit Lite, created for Minecraft 1.4.7, features 48 total mods. The most recent release of Tekkit is designed for 1.6.4 and is the largest mod pack of the three with 62 total mods. Many of the mods used in Tekkit Lite and Tekkit overlap with the mods of Tekkit Classic.
All versions of Tekkit use the Minecraft Technic Launcher to download and install.