It turns out that I’ve given authorization to apps and websites which I don’t remember why and when I gave to them. I don’t even remember what these do. Now, I remember that I don’t need these apps and websites anymore. So, the action is to revoke the access. If you ever wonder why I should revoke the access, here’s why: these apps and sites (that I’ve given my authorization) are using oAuth service so that you (and I) get an easy way to handle authorization process.