Explain like I only speak in plain English

Bundler ensures a Ruby project is run in the same condition on different machines consistently. It does this by keeping track of a list of Gems and their versions required for a project to run correctly.

Bundler is often used together with RubyGems in Ruby projects. When an engineer starts work on an existing project for the first time, he/she will often use Bundler to install all the necessary Gems required by the project.

Bundler can also be used to update a collection of Gems. Bundler makes sure updated versions of different Gems are compatible with each other.

Explain like I'm a total nerd

RubyGems deals with the creation, distribution, versioning of individual Gems. Bundler deals with a collection of Gems required by a project.

Bundler tracks all the Gems used in a Ruby project in a file called "Gemfile". When an engineer starts work on an existing project for the first time. He/she will use Bundler to install all the Gems defined in the Gemfile.

Bundler is also a Gem itself. You can install or update Bundler using RubyGem command line tools.

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Explain like I already know it

Most of the time a project doesn't behave properly because we forgot to update or install Gems. `bundle install` is often the remedy to our headaches.

Ruby on Rails

Ruby on Rails is a web application framework built using the programming language Ruby. It is very popular amongst early stage startups with small teams as you can create a working website very quickly.

RubyGems

RubyGems is a package manager for Ruby libraries. RubyGems is used to deal with installation, removal, updates of Ruby libraries. RubyGems libraries are called Gems for short.

Ruby

Ruby is a general purpose programming language that you can use to write all sorts of programs. It is the base language of the popular web applications framework called Ruby on Rails.