Is a token which differs from a cryptocurrency as its value is related to its function within a particular ecosystem and not limited to one role (cryptocurrency serve only as an exchange of value) but may offer stake, voting rights or anything that a company decides to offer those who own their token(s). The U.S. Securities and Exchange Commision uses the “Howey Test” to determine if a token meets their standard of a security.
A strategy in which a group of miners collaborates to increase their revenue. The miners hide new blocks and only make them available to systems within their private network. Selfish mining is not good for a cryptocurrency's decentralized nature, and the scenario could result in selfish mining becoming a majority of the public blockchain.