Bundler is a gem that installs all gems in your Gemfile. While you don’t have to use Gemfile and bundler, it is highly recommended as it ensures you’re running the same version of Jekyll and its plugins across different environments. Install Bundler using gem install bundler. You only need to install it once, not every time you create a new Jekyll project. Bundler is the standard tool for managing Ruby project dependencies.
Gem
Gems are code you can include in Ruby projects. Gems package specific functionality. You can share gems across multiple projects or with other people. Gems can perform actions like converting a Ruby object to JSON, pagination, interacting with APIs such as GitHub and more. Jekyll is a gem. Many Jekyll plugins are also gems, including jekyll-feed, jekyll-seo-tag and jekyll-archives.
Gemfile
A Gemfile is a list of gems used by your site. Every Jekyll site has a Gemfile in the main folder.
Jekyll
Jekyll is a static site generator. It processes your site by converting Markdown and Liquid files into static HTML. It is written in Ruby
Liquid
Liquid is an open-source template language created by Shopify and written in Ruby. It is the backbone of Shopify themes and is used to load dynamic content on storefronts. Liquid has been in production use at Shopify since 2006 and is now used by many other hosted web applications.