Most programming and markup languages support the notion of “comments”, or regions of code which are ignored by the compiler/interpreter. jEdit has commands which make inserting comments more convenient.
Comment strings are mode-specific, and some in some modes such as HTML different parts of a buffer can have different comment strings. For example, in HTML files, different comment strings are used for HTML text and inline JavaScript.
>> (shortcut:
C+e C+c) encloses the selection with comment start and
end strings, for example /* and */
in Java mode.
>> (shortcut:
C+e C+k) inserts the line comment string, for example
// in Java mode, at the start of each selected
line.
You might be looking for the actions or . They are available from the TextTools plugin, not jEdit core.