Spotlight

Spotlight is the system's default answer to "where is that thing." A keystroke drops a centered search field, and results stream in as you type, grouped by kind — top hit, applications, documents, definitions, web suggestions. The top-hit logic is the whole experience: it bets on a single best match and lets you commit with Enter before you finish typing, which makes launching apps feel instant. It also folds in calculations, unit conversions, and dictionary lookups inline, so the search box doubles as a scratchpad. Where it frustrates is opacity and drift. Ranking changes without explanation, web results sometimes outrank local files you clearly meant, and the lack of user-visible scoping means you can't always force it to look only where you know the answer lives.