funny looking comments - c++

when i read through source files of opensource projects i often come across some weird phrases in the comments

/*       
@brief ......  
@usage.....  
@remarks....  
@par....  
*/

questions

1.What are they?(were not mentioned when i was learning c++)

2.Do they have any documentation(where)

They are just comments and as such have no special meaning in C++. They are probably to allow a documentation generator (For example Doxygen) to extract the data from the comments.

Those are for some flavour of automatic documentation generator. Another program runs through the code looking for comments of like you see there. The @... keywords identify how the documentation should be laid out, and that program generates pretty HTML or printed documentation directly from the source code. It's a way to keep the docs up-to-date with the code more easily.