The BEAM (Bogdan/Björn's Erlang Abstract Machine) is the virtual machine that runs Elixir and Erlang code. It provides lightweight processes, garbage collection, and concurrency support.

The BEAM, short for Bogdan/Björn's Erlang Abstract Machine, is the underlying virtual machine that executes Elixir and Erlang code. One of its most notable features is its support for lightweight processes, which allow Elixir to handle a large number of concurrent tasks efficiently. Each process in the BEAM is isolated, has its own memory, and communicates with other processes through message passing, enabling robust concurrency without the complexities of shared state management. This model is particularly well-suited for building scalable and fault-tolerant applications. The BEAM's garbage collection mechanism is also optimized for low-latency performance, as it uses a per-process garbage collector that minimizes pause times. This design choice helps maintain high throughput even under heavy loads. Additionally, the BEAM provides features such as hot code swapping, allowing developers to upgrade their applications without downtime—a crucial requirement for many real-time systems. This capability enhances Elixir's use in telecoms and distributed systems, where reliability and uptime are paramount. Overall, the BEAM is a key reason why Elixir is regarded as an excellent choice for concurrent, distributed, and fault-tolerant applications.