Dragon's Den investors usually request equity in exchange for providing business funding.
Equity means an ownership share in a company. When a Dragon offers money for equity, the entrepreneur is proposing to give the investor a percentage of the business. The percentage depends on the valuation negotiated during the pitch, and the final terms may differ from the entrepreneur's opening request.
This structure explains why valuation is such a prominent part of the programme. A request for a fixed amount of money in return for a stated percentage implies a particular value for the whole company. The Dragons can challenge that valuation, make a different offer, or decline to invest.
Equity is not the same as a salary, patent or donation. A salary pays for work, a patent protects an invention, and a donation does not normally buy ownership. On Dragon's Den, the essential exchange is investment capital for a stake in the business, sometimes alongside advice and commercial connections.