What is Gemfile.lock? or What is the difference between Gemfile and Gemfile.lock? These are the common questions that you come across while starting development with Rails project.

What is Gemfile?

• Gemfile is the file in which you can mention which gems (kind of Third Party libraries) that you want to use for your Rails application
• Gemfile lists the gems that you want to use for your development
• Syntax:

gem 'rails'

• This mentions that gem with name ‘rails’ has to be used in Project context
• Whenever you bundle install, then bundler finds the gems listed in the Gemfile and it installs latest stable version for the gems listed in the Gemfile
• You can specify which version to be used for the rails development:

gem 'rails', '3.0.5'

• • This will install the specific version of the rails i.e. version 3.0.5
• You can read more regarding Gemfile here

What is Gemfile.lock?

• Gemfile.lock is created when bundler installs the specific version for the gems that are listed in Gemfile
• It records the version of the gem and name of the gem in file Gemfile.lock
• Thus, Gemfile.lock contains actual gem name with version with which your application was configured by the bundler
• Thus, Gemfile.lock is the file with actual gem version configuration
• Thus answer to what is gemfile.lock is - File with gems configured for your Rails applications along with the exact versions
• This file can be updated when you change gems listed in the Gemfile and also updating it using the bundler