A more thorough explanation:

A trade guild is a group of people who work in the same profession or craft and come together to regulate and protect their trade. It is a voluntary society or fraternity where members pay a fee for its general expenses. The main purpose of a trade guild is to promote and protect the interests of its members.

For example, a group of blacksmiths may form a trade guild to regulate the quality of their work, set prices, and protect their trade secrets. The guild may also provide training and apprenticeships to new members to ensure that the craft is passed down to future generations.

In medieval times, trade guilds were very common. For instance, the London Company of Mercers was a powerful trade guild that controlled the import and export of luxury goods such as silk and spices. The guild also had a lot of political influence and played a significant role in the governance of the city.

These examples illustrate how trade guilds work to protect and promote the interests of their members. By coming together, members can regulate their trade, set standards, and ensure that their craft is passed down to future generations.