Llama 2

Announced July 18, 2023 in partnership with Microsoft, Llama 2 was the release that turned open weights from a research curiosity into a commercial foundation. Unlike the leaked, research-only Llama 1, Llama 2 shipped in 7B, 13B, and 70B sizes with a Community License permitting commercial use (for organizations under 700M monthly active users), trained on 2 trillion tokens with RLHF-aligned Chat variants.

Llama 2 became the base for thousands of fine-tunes — including Code Llama, Vicuna v1.5, and countless community models — and legitimized building products on open weights for mainstream enterprises. Its license is not OSI open source (acceptable-use policy restrictions apply), a nuance worth noting. It was succeeded by Llama 3 in 2024 but remains one of the most-downloaded model families in history.