What Does Level 1 Cache (L1 Cache) Mean?

A level 1 cache (L1 cache) is a memory cache that is directly built into the microprocessor, which is used for storing the microprocessor’s recently accessed information, thus it is also called the primary cache. It is also referred to as the internal cache or system cache.

Techopedia Explains Level 1 Cache (L1 Cache)

In more recent microprocessors, the L1 cache is divided equally into two: a cache that is used to keep program data and another cache that is used to keep instructions for the microprocessor. Some older microprocessors, on the other hand, make use of the undivided L1 cache and uses it to store both program data and microprocessor instructions.