There are two main components to a kitchen sink drain. The basket strainer inserts into the hole in the sink and provides the connection for the tail piece and trap. The second component would be the trap, the main function of the trap is to seal off the drain from sewer gases. Also most strainers will come with a compression nut and a plastic gasket specially designed for kitchen sink tail pieces. Tail pieces for kitchen sinks have a flange at the top specially designed to adapt to kitchen sink basket strainers.
Also you may have a garbage disposal and/or connections for a dishwasher. Garbage disposers require a special basket strainer for connecting a garbage dispoal to the sink. If you plan on removing the garbage disposal and not reinstalling one, you will need a standard basket strainer and possibly a new end outlet waste drain to reconnect the drain.
When installing a new kitchen sink, before you set the sink into the counter install the faucet, basket strainers, and connect the water lines to the faucet. Installing these connections before setting the sink into the counter top will prevent you from having to make these connections under the sink with limited space.
If you have a question about kitchen sink drains or another repair post it in the user feedback.
