to send an electronic document with an email

I attach a copy of the spreadsheet.

I am attaching the image as a PDF file.

to believe that something is important or worth thinking about

I attach great importance to this research.

I wouldn't attach too much weight to these findings.

to join somebody for a time, sometimes when you are not welcome or have not been invited

He attached himself to me at the party and I couldn't get rid of him.

to be connected with somebody/something; to connect something to something

No one is suggesting that any health risks attach to this product.

This does not attach any blame to you.

Unfortunately, there is still a stigma attached to mental illness.

LEARNit Dictionary