Gemfile and Gemfile.lock

Gemfile

Simply put, Gemfile is a format for describing gem dependencies for Ruby programs. Or you can say it contains the gems you need in this project.

Gemfile.lock

Gemfile.lock is a file records exact versions of all the gems you used the last time you know for sure that the application worked.

If there is error during the first time you install the gem, noGemfile.lockfile will be created. After you create yourGemfile.lock, every time you update, add or remove some gems install that, the Gemfile.lock will modify the version of the gem.

Again, if there is any error occurs while installing, theGemfile.lockwill not be updated and remained as the last state.

The reason Gemfile.lock is important is when other developers fork your project, theGemfile.lock can make sure after they run bundle install, the app can run on their computers. Instead of installing the latest version of each gem then breaks the app.

Resource: What is Gemfile

Resource: Gemfile