A mode found in some applications for locating a text string within a document. The mode is generally invoked by hitting a key or key combination; the user then begins typing a string. The cursor moves ahead through the document to the first instance of the complete string so far typed (possibly highlighting it).

Example: a document containing the sentence "The Queen thought it was quite quick." Entering IncrementalSearch mode, the user types ''q''; the cursor jumps to the ''Q'' in ''Queen''. Typing a further ''u'', the cursor moves to the ''u'' of ''Queen''; typing an ''i'' (making the search string so far ''qui''), it jumps to the ''i'' in ''quite''; typing a ''c'', it jumps to the ''c'' in ''quick''.

In MozillaFirefox this mode is known as "Find as you Type".

In EmacsEditor, you hit C-s to start searching. As soon as you type a character, emacs finds the next occurrence of that character and highlights it. As you type more characters, Emacs moves (if need be) to the next occurrence of the entire string of characters. So if you go to the beginning of this paragraph and hit "C-s e", it'll put you at the beginning of the second word; if you then hit "a", it'll put you at the first ea (in the word "searching"); if you then hit "r", you stay in the same place, but the r is also highlighted; if you hit C-s again, Emacs puts you at the "ear" in the occurrence of the word "searching" further down in the paragraph.

This makes searching for text with a dialog box and buttons seem painfully slow and awkward by comparison. Many Emacs users have been known to navigate with isearch instead of reaching for the mouse, because it's so fast.

Applications that have incremental searches:
* DevCpp 
* EmacsEditor
* VimTextEditor
* JoesOwnEditor
* MozillaFirefox
* WikiPad
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Note that Firefox has severe usability drawbacks in "Find as you Type": the search box disappears after a few seconds, and you must use the mouse/keyboard to get it back (sometimes several times). Since it can take several seconds to identify where the highlighted term is, this cure is almost worse than the problem. Additionally, the Highlight All option cannot be set as default, making it an extra click for every search by users who prefer it.

''To get past that, simply press Ctrl+F to bring up the search box as normal and IncrementalSearch as you please.''