To attach means to fasten or connect one thing to another. When you attach a photo to an email, you're adding it so it travels along with your message. When you attach a name tag to your backpack, you're securing it so it stays connected.

The word works for both physical and digital connections. You might attach a trailer to a truck with a hitch, attach papers together with a staple, or attach a file to a homework assignment you're submitting online. Scientists attach sensors to animals to track their movements, and builders attach boards together with nails or screws.

The word can also describe emotional connections. When people become attached to a pet, they develop strong feelings of affection and care. You might feel attached to a favorite stuffed animal from childhood or a book you've read many times. This kind of attachment means you feel connected to something in a way that makes it hard to let go.

An attachment can be the physical piece that connects things, like the beater attachment on a mixer, or it can be the file you send with an email. People also use the word detach for the opposite: separating things that were connected.