I think, occasionally, it's a lot easier to grok a command through googling than reading the built-in help. A fair amount of built-in *nix documentation I have run across is mediocre or unhelpful.
"regexsearch" is more work to type and more space taken up everytime 'grep' appears in a command-line. And says nothing about recursion.
Edit: the rest of my comment (somehow submitted to soon!)
man grep
/recurs<enter> $ man grep | grep recursive
directory, recursively, following symbolic links only if they
Exclude directories matching the pattern DIR from recursive
-r, --recursive
Read all files under each directory, recursively, following
-R, --dereference-recursive
Read all files under each directory, recursively. Follow all