Boost
Boost is a collection of peer-reviewed, portable C++ libraries that provide support for tasks such as linear algebra, multithreading, image processing, and unit testing. It serves as a de facto standard extension to the C++ Standard Library, offering high-quality, cross-platform components that are widely used in both open-source and commercial projects. Many Boost libraries have been incorporated into the C++ standard (e.g., smart pointers, regular expressions, and threading).
Developers should learn Boost when working on C++ projects that require robust, well-tested libraries for advanced functionality not yet available in the standard, such as graph algorithms, asynchronous I/O, or metaprogramming. It is particularly valuable in performance-critical applications like game development, financial systems, and scientific computing, where its efficiency and reliability are key. Using Boost can accelerate development by providing ready-made solutions that reduce the need for custom implementations.