Some pretty common and not so common hardware terms and their meanings.
ROM (Read Only Memory) is a non volatile memory, generally installed by the vendor of the computer during the process of manufacturing the motherboard or secondary components that need to retain the code when the machine is turned off. ROM holds the instructions for performing Power on Self Test (POST) and the Basic Input-Output System (BIOS) information for a smoother startup to the computer.
RAM (Random Access Memory) is the memory when we discuss it. It is a volatile memory that holds temporary data for manipulation while the system is running. If power to the system is lost, all RAM is lost too. There are 3 types of RAM avaliable in the market, SDRAM (Synchronous RAM), DRAM (Dynamic RAM) and RDRAM (Rambus Dynamic RAM).
This is memory that is set aside for anticipated use. It is to hold recently or frequently used code or data for rapid retrieval. This is set on the CPU (Central Processing Unit) of the computer.
The original onboard cache is known as the L1 or Level 1 cache or Internal cache. All commands of the computer go through the cache.
This is additional cache added onto the motherboard outside the CPU. This is also called L2 or Level 2 or External cache.