Types

A basic time clock will just stamp the date and time on a time card, similar to a parking validation machine. These will usually be activated by a button that a worker must press to stamp their card, or stamp upon full insertion. Some machines use punch hole cards instead of stamping, which can facilitate automated processing on machinery not capable of optical character recognition. There are also variations based on manufacture and machine used, and whether the user wants to record weekly or monthly recordings. The time cards usually have the workdays, "time in", and "time out" areas marked on them so that employees can "punch in" or "punch out" in the correct place. The employee may be responsible for lining up the correct area of the card to be punched or stamped. Some time clocks feature a bell or signal relay to alert employees as to a certain time or break.^{[citation needed]}
Fraudulent operation of time clocks can include overstamping, where one time is stamped over another, and buddy stamping, where a friend clocks in another member of staff.
Self-calculating machines are similar to basic time clocks. Nevertheless, at the end of each period the total time recorded is added up allowing for quicker processing by human resources or payroll. These machines sometimes have other functions such as automatic stamping, dual-colour printing, and automated column shift.^{[citation needed]}
Software based time and attendance systems are similar to paper-based systems, but they rely on computers and check-in terminals. They are backed up with software that can be integrated with the human resources department and in some cases payroll software. These types of systems are becoming more popular but due to high initial costs they are usually only adopted by large business of over 30 employees. Despite this they can save a business a lot of money every year by cutting down errors and reducing administration time.[cita