OpenMMLab welcomes everyone who is interested in contributing to our projects and accepts contribution in the form of PR.
## What is PR
`PR` is the abbreviation of `Pull Request`. Here's the definition of `PR` in the [official document](https://docs.github.com/en/github/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests) of Github.
```
Pull requests let you tell others about changes you have pushed to a branch in a repository on GitHub. Once a pull request is opened, you can discuss and review the potential changes with collaborators and add follow-up commits before your changes are merged into the base branch.
```
## Basic Workflow
1. Get the most recent codebase
2. Checkout a new branch from `main` or `dev-1.x` branch, depending on the version of the codebase you want to contribute to (see [Maintenance Plan](../migration/overview.md) for more details)
3. Commit your changes ([Don't forget to use pre-commit hooks!](#3-commit-your-changes))
4. Push your changes and create a PR
5. Discuss and review your code
6. Merge your branch to `main` or `dev-1.x` branch
## Procedures in detail
### 1. Get the most recent codebase
- When you work on your first PR
Fork the OpenMMLab repository: click the **fork** button at the top right corner of Github page
Checkout the latest branch of the local repository and pull the latest branch of the source repository. Here we assume that you are working on the `dev-1.x` branch.
```bash
git checkout dev-1.x
git pull upstream dev-1.x
```
### 2. Checkout a new branch from the `main` branch or `dev-1.x` branch
```bash
git checkout -b branchname
```
```{tip}
To make commit history clear, we strongly recommend you checkout the `main` or `dev-1.x` branch before creating a new branch.
```
### 3. Commit your changes
- If you are a first-time contributor, please install and initialize pre-commit hooks from the repository root directory first.
```bash
pip install -U pre-commit
pre-commit install
```
- Commit your changes as usual. Pre-commit hooks will be triggered to stylize your code before each commit.
```bash
# coding
git add [files]
git commit -m 'messages'
```
```{note}
Sometimes your code may be changed by pre-commit hooks. In this case, please remember to re-stage the modified files and commit again.
```
### 4. Push your changes to the forked repository and create a PR
- Push the branch to your forked remote repository
- Revise PR message template to describe your motivation and modifications made in this PR. You can also link the related issue to the PR manually in the PR message (For more information, checkout the [official guidance](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue)).
- Specifically, if you are contributing to `dev-1.x`, you will have to change the base branch of the PR to `dev-1.x` in the PR page, since the default base branch is `main`.
