TeX is a typesetting system invented by D. E. Knuth. MiKTeX (pronounced mik-tech) is an implementation of TeX and related programs.
MiKTeX is available for Windows, macOS and selected Linux distributions. Its main features include:
Easy to install
Integrated package management: MiKTeX's integrated package manager installs missing components from the Internet, if required. This allows users to keep the TeX installation as minimal as possible (“Just enough TeX”).
Complete: the MiKTeX distribution contains almost all packages that are freely redistributable.
Always up-to-date: the MiKTeX package repository is updated regularly and MiKTeX provides tools to easily install package updates.