BitBucket is an online code hosting platform that allows for collaboration on code repositories. It provides version control through Git or Mercurial and allows users to store code repositories privately or publicly. The document outlines the benefits of hosting code online through source control, including having backups, allowing collaboration and receiving feedback. It then defines key terms related to BitBucket and version control like repository, fork, clone, commit, push and pull. Finally, it provides step-by-step instructions for creating a repository, cloning a repository locally, adding code to a repository and cloning a forked repository. The benefits of BitBucket are listed as having backups of code, avoiding conflicts through collaboration, and its effectiveness for large open source projects.