How to see what mapping for a particular key in vim?

Question

I would like to know what <leader>a is mapped to in my vim. Is there a command to know this?

Answer 1

Use :map <leader>a to get a list of all mappings having that specific prefix.

from :h :map

        List all key mappings for the modes where the map
        command applies.  Note that ":map" and ":map!" are
        used most often, because they include the other modes.