How do I know when a computer was purchased?

All Dell computers have a seven character Service Tag.

On desktop computers the tag is usually a black sticker with white writing and can be found on the top, front edge of tower computers that are standing or the left, front of a desktop laying on its side.

All-in-One computers can have the tag on the back, near the bottom left or on the bottom of the front bezel. For ease of access for computers with the service tag on the bottom of the front bezel, we recommend using the front facing camera on a phone to take a picture of the tag.

Laptop Service Tags can be found on the bottom.

Visit http://dell.com/support and enter the Service Tag. On the resulting page, go to the Warranty link and the original ship date along with the warranty expiration date will be displayed.