Jekyll (software)
Jekyll is a simple, blog-aware, static site generator for personal, project, or organization sites. Written in Ruby by Tom Preston-Werner, GitHub's co-founder, it is distributed under the open source MIT license.

History
Jekyll was first released by Tom Preston-Werner in 2008. Jekyll was later taken over by Parker Moore, who led the effort in releasing Jekyll 1 and has been the new maintainer since then. 

Jekyll started a web development trend towards static websites. As of 2017, Jekyll is the most popular static site generator, largely due to its adoption by GitHub.

Features
Instead of using databases, Jekyll takes the content, renders Markdown or Textile and Liquid templates, and produces a complete, static website ready to be served by Apache HTTP Server, Nginx or another web server. Jekyll is the engine behind GitHub Pages, a GitHub feature that allows users to host websites based on their GitHub repositories for no additional cost.

Jekyll is flexible and can be used in combination with  front-end frameworks such as  Bootstrap, Semantic UI and many others.

Jekyll sites can be connected to cloud-based CMS software such as CloudCannon, Forestry, Netlify or Siteleaf, enabling content editors to modify site content without having to know how to code.

Philosophy

According to Jekyll's "README" file,
Jekyll does what you tell it to do — no more, no less. It doesn't try to outsmart users by making bold assumptions, nor does it burden them with needless complexity and configuration. Put simply, Jekyll gets out of your way and allows you to concentrate on what truly matters: your content.