OpenDescMap is a collection of descriptions (descs) displayed on a map.
You may double-click anywhere on the map to add a description of that location. The desc may be some text or a simple link to an external Web page. Your desc may (and should) be subjective: objective information should be stored in OpenStreetMap or Wikipedia. You may use OpenDescMap as a kind of diary organized not by date but by location, or as a repository for notes that you want to associate with some location.
OpenDescMap lets you read descs written by other people, as well as other sources of information such as OpenStreetMap or Wikipedia.
Therefore OpenDescMap is another way to look at places and writing about them.
By default, you will use the collective "Everybody" identity, which means that your contributions and settings can be modified by everybody else.
Or you may use your own identity by creating an account or logging through your Facebook or Twitter account. Then you can may publish descs in three modes: private (only visible by you), public (published with your name or pseudonym) or masked (published with no name).