15.1 Incremental Search
The principal search command in Emacs is incremental: it
begins searching as soon as you type the first character of the search
string. As you type in the search string, Emacs shows you where the
string (as you have typed it so far) would be found. When you have
typed enough characters to identify the place you want, you can stop.
Depending on what you plan to do next, you may or may not need to
terminate the search explicitly with RET.
C-s
Incremental search forward ( isearch-forward).
C-r
Incremental search backward ( isearch-backward).
You can also invoke incremental search from the menu bar’s
‘ Edit->Search’ menu.