the central processing unit or CPU is the key device of a computer, the part that is analogous to the human brain. the CPU acts upon the instructions of software to:

manipulate data
perform arithmetical computations
direct the function of other hardware devices

different types of processors have their internal electronics arranged in different ways. this is referred to as the process's architecture. the CPU, along with all the other small devices that suport its functining, make up the system built around the need of a processor. this system is often called a platform. Linux is available for many different platforms, including processors like: SPARC which stands for: Scaleable Process ARChiteture, ALPHA and INTEL

INTEL is the most widely use in linux

procesors today usualy work iwth 32 or 64 bits of information at a time. most intel processors, such as the Pentium procesors, are 32-bit CPUs, they are much cheapter the the 64-bit such as the Intel Itanium, SPARC and Alpha processors are 64bit.

what else you want to learn about CPUs?