Gradle tip - Always use a gradle wrapper

The wrapper sits in your project and defines a common build behaviour for all your team and CI tools. 

Why not use a local gradle installation? 
A. You will find yourself out-of-sync with other team members
B. You won't be able to run your project without pre-installing stuff (bad for CI implementations)
C. Your project build behaviour won't be tracked in git, which will cause problems going back to old revisions.

A gradle wrapper version is set in gradle-wrapper.properties - Only thing that needs to change in a gradle wrapper is the distributionUrl. It marks which gradle version should be used.

Gradle tip - What is gradle anyway?

Gradle is a build system. Android, along with the Android Studio, uses Gradle as its main build system, and adding functionality through an Android plugin. 

If you developed in the Eclipse days, than you would be familiar with Eclipse as your main build system. If you come from Web development background, than Gradle is your Grunt.

Gradle is based on the Groovy language, allowing us to write rich, scalable, scripts.

Gradle will be automatically ran with your Android Studio builds, but it can also be accessible via the command line/terminal, allowing you to integrate it easily with your CI.