Bootstrap is a free front-end framework for faster and easier web development and it is the latest version of the Bootstrap front-end framework, released in 2017. It is a collection of CSS and HTML conventions used for the styling and layout of web pages. Like its predecessor, Bootstrap 4 is designed to be responsive, meaning that the layout of a webpage built with Bootstrap will automatically adjust to look good on any device, whether it be a desktop computer, a tablet, or a smartphone.