L3

L3 is a designation used in multiple domains to denote Level 3 or Layer 3 concepts, as well as several proper nouns. Its meaning depends on context.

Computing: Level 3 cache, a large, slower memory cache shared by cores, positioned between L2 caches and main memory; it reduces latency of memory access and improves throughput. Sizes vary, typically from a few megabytes to tens of megabytes.

Audio encoding: Layer III (L3) in the MPEG family; an audio coding layer that achieves high compression. MP3 is the best-known format that uses Layer III, widely used for digital music and streaming.

Linguistics: L3 stands for a third language learned after a person’s native language (L1) and second language (L2); researchers study transfer effects and cognitive demands in multilingual acquisition.

Anatomy: L3 is the third lumbar vertebra in the lumbar spine, or the L3 spinal nerve that emerges at that level; it plays a role in lower-back function and leg sensation and movement.

Defense industry: L3 Technologies was a defense contractor that merged with Harris Corporation to form L3Harris Technologies in 2019; the L3 name appears in legacy brands and product lines.

Mathematics: In functional analysis, L^p denotes Lebesgue spaces; L^3 denotes the space of functions whose absolute value is cube-integrable, sometimes written as L3 in informal contexts.