01In plain English
OAuth is the standard that lets one app get limited access to your account on another, without you handing over your password. When a tool asks you to "connect your Google account" and shows a list of what it wants to access, that is OAuth.
02How it works
When you click Sign in with Google or Connect your calendar, the app sends you to the provider's own page, not its own. There you log in as usual and see a list of what the app is asking for, such as reading your email or seeing your calendar events. If you approve, the provider hands the app a token, which is like a visitor pass limited to those permissions. The app uses the pass instead of your password and never sees the password itself. You can cancel the pass at any time from your account settings, and it can also expire by itself. A hotel key card works the same way: it opens one door for a set time, without handing over the master key.
03Why it matters when you are choosing
It is how most tools and AI agents reach your email, calendar or files. The permissions you approve on that screen decide what the tool can read and change, so it is worth reading before you click Allow.
04What to check
Read the permission list before approving. Check you can see and remove connected apps later from your account settings.
05Where you will meet it
06Common questions
Is OAuth the same as signing in with a password?
No. With a password, you give the app your login. With OAuth, you log in at the provider and the app only receives a limited pass. The app never sees your password, and you can cancel its access later without changing the password itself.
How do I remove an app's access to my account?
Open the security or connected apps section of the account you signed in with, such as your Google or Microsoft account, find the app in the list and choose to remove access. That cancels the pass immediately. Do this for tools you no longer use, since old connections stay active otherwise.
Is it safe to click Allow on an OAuth screen?
It is as safe as the permissions you approve. Read what the app asks for and compare it with what the tool needs to do its job. A notetaker needing calendar access makes sense, while one wanting to send email as you or delete files deserves a second look before you agree.