I didn't find the difference between them by googling

Edit: Thx litterally, authenticate, means prove its identity, which is a just a subprocess of global access authorization
btw I forgot to mention "Sign In", that's another confusing term for me ;)

Edit 2
other useful answers: https://ux.stackexchange.com/questions/1080/using-sign-in-vs-using-log-in

  • Logging in is the "containing" process that covers many things besides actually having your login credentials authenticated. But in many contexts, "authentication" is seen as the most important part of that process, so it's used to mean everything else as well. Commented Sep 6, 2012 at 22:56
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    Cyril, Cyril, Cyril – You've made the same mistake I've seen many others make here: you've made your question more interesting in your comments, after you started answering the queries posed by others, instead of putting that crucial information in your original question. I hope that, if you ask other questions in the future, you'll try to elaborate a bit more from the very beginning.
    – J.R.
    Commented Sep 6, 2012 at 23:44
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    As far as English is concerned, there is a world of difference between "authenticate" and "log in". The former is something you might try to do with that movie poster or vase you acquired at a yard sale, whereas "log in" is meaningless in that context. In other words, this question (as clarified in the comments) is off topic.
    – Marthaª
    Commented Sep 7, 2012 at 0:05
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    In most cases logging in requires 2 steps: identification and authentication.
    – gam3
    Commented Sep 9, 2012 at 4:53
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    this is badly flagged, this isn't general reference. it can't be definitively and permanently answered, as evidenced by the constant, ongoing debate over which is the right one to use in user interfaces: ux.stackexchange.com/questions/1080/…
    – mendota
    Commented Sep 5, 2018 at 19:06

1 Answer 1


To "authenticate" is to verify the credentials of a user; in normal circumstances checking that the password supplied for the given username is correct. Sometimes this also includes making sure the user is permitted to enter the particular part of the site which they requested to enter (some areas could be restricted to certain users, for example).

To "log in" is to enter a site using certain credentials. This word describes what the user does in order to be authenticated by the site; in normal circumstances entering the username and password, and clicking a button. To be logged in is to have already been authenticated by the site, and usually means you get different pages given to you (ones that are customised).

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    You can log in without any credentials, say, in a zero-security environment where users fully trust each other, you only give your handle and you're logged in without authentication. And you can authenticate without logging in: sign a single transaction with your credentials, the transaction is then accepted and executed but you're not logged in. These are two different things that simply happen combined together frequently (usually login without authentication is not permitted.)
    – SF.
    Commented Sep 7, 2012 at 7:48
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    This is not a bad answer except that it should cite reliable sources that can be used to verify the claims made in it.
    – MetaEd
    Commented Sep 7, 2012 at 7:56
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    @Cameron, what about sign in?
    – XPMai
    Commented Dec 7, 2015 at 3:15

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