Readers fill in their name, address, and telephone number, circle numbers corresponding to advertisers they are interested in, and mail back the card to the publisher, who in turn forwards readers' contact information to the selected advertisers.
Before the World Wide Web was invented, reader service cards relieved consumers (as well as business executives with purchasing authority) of the inconvenience of having to separately contact each advertiser in a particular magazine by mail, fax, telex or telephone to express interest.
Instead, they would just mail a reader service card back to the publisher.
[2] Over the next few weeks, fat envelopes containing brochures, pamphlets, catalogs, and product samples would arrive in the mail from the selected advertisers.
This was a common method for gathering an up-to-date collection of mail order product catalogs and product literature in preparation for a purchasing decision before web sites became the primary delivery vehicle for such information.