Parallel algorithms are algorithms that use parallelism to execute multiple computations or processes at the same time. They are essential for high-performance computing, where large and complex datasets need to be processed efficiently. There are several synonyms for the term "parallel algorithms," including concurrent algorithms, simultaneous algorithms, multi-core algorithms, and distributed algorithms. Concurrent algorithms execute different parts of a program simultaneously, while multi-core algorithms use multiple processors to execute a program. Simultaneous algorithms use multiple threads to perform multiple processes at the same time while distributed algorithms execute a program across multiple computers, often over a network. Understanding these synonymous terms is essential to stay up-to-date with the latest developments in the field of parallel computing.