To sink the heat.
A heat sink is designed to disperse and transfer heat coming from a processor to an outside medium, so that it does not overheat the actual processor chip. It is usually used in conjunction with a fan to cool the device it is installed on.
To cool the processor
heat sink
It keeps your processor from melting. Do not run a PC without a heat sink on your processor. Processors can get to extremley high temperatures. The heat sink absorbs this heat and removes it using a fan.
The heat sink absorbs the heat from the processor and then the fan disperses the heat.
Heat sink
A heat sink is a device commonly used to help move heat away from a processor. It consists of metal fins that absorb and dissipate heat generated by the processor through conduction and convection. In some cases, a fan is attached to the heat sink to enhance heat dissipation.
sink
If you buy a retail boxed processor, yes. You do get a heatsink fan (HSF) with the processor.
The main purpose of a heat sink is to expel heat from a generating source. Heat sinks work through the process of conductive and convection heat transfer. Heat sinks are a passive form of cooling, as they have no moving parts and require no power.
If you change the processor to one that generates more heat than the sink can dissipate you will need to put a larger sink in your computer, but if the processor is the same and you haven't overclocked or anything, the sink will last forever. It's made from cast aluminum and just sits there. It won't wear out.
Processor, RAM, daughter cards, CMOS, Heat sink