Proof of stake (PoS) is a type of algorithm by which a cryptocurrency blockchain network aims to achieve distributed consensus. In PoS-based cryptocurrencies, the creator of the next block is chosen via various combinations of random selection and wealth or age (i.e., the stake). In contrast, the algorithm of proof-of-work-based cryptocurrencies such as bitcoin uses mining; that is, the solving of computationally intensive puzzles to validate transactions and create new blocks. source:
wikipedia
A proof-of-work (PoW) system (or protocol, or function) is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer. source:
wikipedia
A proof of concept (POC) is a demonstration, the purpose of which is to verify that certain concepts or theories have the potential for real-world application. POC is therefore a prototype that is designed to determine feasibility, but does not represent deliverables.
Proof of concept is also known as proof of principle. source:
techopedia