Twitter recently rolled out a new authentication mechanism that allows applications to authenticate users without the need to provide their twitter password.
However once you provide access to a application they have access to your data and account, and can also have write permissions to your account, which means that they can send out tweets on your behalf without you knowing.
Though the chances of that happening is pretty less, however you can revoke access to applications in twitter by following the simple steps given below.
Step 1: Login to your twitter account.
Step 2: Click on the settings link in the top right hand side.
Step 3: In the settings page click on the connections tab to view all the applications that have access to your account.
Step 4: Click on the revoke access links for the application you want to remove permission for.
That’s it the application will no longer have permission to access your account.