For the purposes of this debate, carbon markets are where carbon credits, or carbon offsets are bought and sold. Businesses and individuals can buy carbon credits from organizations that engage in green activities that remove carbon from the environment [either directly e.g. by replanting trees, or indirectly by not polluting e.g. by conserving a rainforest rather than clearing it for development]. Buying carbon credits are a key part of businesses and national governments hitting their net zero targets.
Voluntary carbon markets operate on an opt-in platform, where entities keen to sell, purchase, finance or support a credit market at a specific price can do so, co-existing with other markets that have their own price point, carbon offset calculation formula, and other traits.