Yarn is a package manager for the JavaScript programming language. It allows developers to automate the process of installing, updating, configuring, and removing software packages retrieved from a global registry. Yarn was developed by Facebook, Google, Exponent and Tilde as an improvement upon what they saw as shortcomings in the npm package manager.
Yarn has gained popularity for its speed, reliability, and security. It uses a deterministic installation algorithm and parallelizes operations, resulting in faster and more reliable builds.
Moreover, Yarn uses checksums to verify the integrity of every installed package before executing its code. This ensures a safer JavaScript environment.