In Alfresco you can use social features to like, favorite, and comment on files and folders.
These social features are available in the file preview screen, in the Site Content dashlet, and in several of the Document Library views. You can select to view just favorite files in several of your user and site dashlets.
Note: You can't add comments if your permission level on the site is set to Consumer. Speak to your Alfresco administrator if you need to change your permission level.