What is return receipt requested mean

sample of PS Form 3804

Complete PS Form 3804 and attach the barcoded portion of the label under the “Return Receipt Requested” endorsement.
Mark mail with “Return Receipt Requested” above the delivery address to the right of the return address.
Complete and attach PS Form 3811,Domestic Return Receipt (see page 4), to the front of the mailpiece, unless doing so would cover the address, in which case affix it to the back of the mailpiece.
Pay the applicable extra service fee.

Available for merchandise sent as Priority Mail, USPS Retail Ground, Media Mail, Library Mail, or Bound Printed Matter*.
PS Form 3811 with recipient’s actual signature is mailed back to you.