Search helps people find information by entering words connected to what they need. It is like asking a librarian for a book by its subject instead of checking every shelf.
A store's search box can help someone find a particular item among many products. Results should match the words closely and give enough detail to choose the right one.
Use a clear label and explain when there are no matches. Search works best when it helps people who already have an idea what they want; categories and navigation help people who are still exploring.