To insert means to put something into something else, fitting it into a specific space or position. When you insert a key into a lock, you slide it into the narrow opening. When you insert a bookmark into a novel, you place it between the pages where you stopped reading. Teachers often ask students to insert their names at the top of their papers.

The word suggests a deliberate action of placing something where it belongs or where you want it to go. You might insert coins into a vending machine, insert a USB drive into a computer, or insert a missing word into a sentence. Writers insert commas into their writing to help readers understand where to pause.

An insert (as a noun) is something designed to be put inside something else. A newspaper might contain advertising inserts, which are extra pages tucked inside. Shoes sometimes have cushioned inserts that make them more comfortable. Board games often include cardboard inserts that organize all the pieces in the box.

The opposite of insert is remove or extract. When you're done with that USB drive, you don't insert it anymore, you remove it. Understanding when and how to insert things properly matters: inserting your answer into the wrong blank on a test, for example, could cost you points even if the answer itself is correct.