Gym (OpenAI Gym)

Gym (formerly OpenAI Gym) is a Python library that provided a universal API for developing and comparing reinforcement learning (RL) algorithms across a diverse collection of environments. While it was historically the standard for RL environments, the `gym` library is no longer actively maintained. All future development and support have transitioned to its successor, `gymnasium`, a drop-in replacement. The last major release of `gym` was version 0.26.2, released in October 2022, which introduced significant breaking API changes.