Help:OAuth

OAuth is a means of giving outside ("connected") applications the ability to perform edits and other actions on your behalf. Using this authentication protocol, you can authorize ("grant") a connected application the ability to act on your behalf without the need to divulge your password.

Connected applications
Connected applications are the third-party websites that you authorise to access your account.

Frequently asked questions
If your question is not answered here, feel free to ask on the talk page and someone will answer it for you.

Is OAuth secure?
Yes.

Firstly, OAuth allows third-party websites to access your account without you having to give them your password. Secondly, each third-party website you authorise is only allowed to take the specific actions you authorised it to, so you can be sure that a website is, say, not accessing your administrator tools if it's only requested basic rights.

How do I remove an application's ability to access my account?
Once an application is deauthorised, it will no longer be able to access your account or take any actions on your behalf. You will have to authorise the application again in order for it to access your account.

Can I change what actions an application can take with my account?
Yes.

Please note that removing some of the permissions you've authorised an application to take may cause the application to stop working properly for you.