Full description
Helm is an Emacs framework for incremental completions and narrowing
  selections. It provides an easy-to-use API for developers wishing to
  build their own Helm applications in Emacs, powerful search tools and
  dozens of already built-in commands providing completion to almost
  everything. It is a must-have for anyone using Emacs as a main work
  environment. Helm has been widely adopted by many Emacs power-users.