Analogue cameras provide composite video over coaxial cables, which are inexpensive and widely available.

Two different types of connectors are found on composite video cables:

BNC

These employ a locking mechanism and are commonly found on professional video equipment.
 

RCA

Push-fit connectors found on both consumer and professional video equipment.
 

Check the connection sockets offered by the analogue cameras and video input hardware you intend to use, so that you can choose cables with the appropriate connectors at each end.

If your cables have the wrong connectors, this can be easily corrected with the use of small adapters, available from many electronics retailers.