/** for commenting vs /*

Hi, I was wondering why comments in UE4 example projects are in the format /**

Why dobule asterisk? It works with just one, It’s a common practice?

Also, for multiline comments they used asterisk in every line.

What about that?

Most IDE’s will view the double asterisk as a documentation comment. Here is a screenshot of an example in Xcode

The asterisk on the following lines are just a convention, eye candy.

/** Calculates something
 *  @Param A A number
 *  @Return 0
 */
int doSomething(float A);

is no different from

/** Calculates something
    @Param A A number
    @Return 0
 */
int doSomething(float A);

Edit:
Please note that UE4 has a header parser that reads theses comments, and can display them in the editor, primarily as tooltips.