Karl Berry Olaf Bachmann and many others.
Incremental searches begin before the user has finished typing the search string.
As each character of the search string is typed, Readline displays the next entry from the history matching the string typed so far. An incremental search requires only as many characters as needed to find the desired history entry. The characters present in the value of the isearch-terminators variable are used to terminate an incremental search. If that variable has not been assigned a value, the ESC and C-J characters will terminate an incremental search. C-g will abort an incremental search and restore the original line.