Tenacity is a Python library that simplifies the task of adding retry behavior to any function or process. It is licensed under Apache 2.0 and fixes many bugs and adds significant new functionality compared to its predecessor, retrying. The library provides a generic decorator API, customizable retrying on exceptions and expected returned results, and the ability to specify stop and wait conditions. Tenacity provides various wait conditions, including fixed wait, random wait, exponential backoff, and exponential jitter. To use Tenacity, simply install it via pip and specify your retry behavior in your code.