Seed is the funding round that usually follows pre-seed. By this point there's normally something to point to: a working product, some early users, or a first sign of revenue, even if it's still small. The money typically goes toward turning that early signal into something more solid, building out the team, refining the product, or reaching the milestones an investor would want to see before a Series A.
Where pre-seed investors were largely backing the founders and the idea, seed investors expect some evidence the idea is working, even if that evidence is thin. That shift, from betting on people to weighing early proof, is what separates the two stages more than anything else.
Not every company raises a distinct seed round. Some fold pre-seed and seed into one larger raise, particularly when the founders are experienced or the product needed less validation up front.
Many seed rounds move from SEIS to EIS. SEIS is only available to companies that have been trading for less than three years and have raised no more than £250,000 through the scheme in total, so a company that used SEIS at pre-seed, or that has simply been trading longer, often no longer qualifies by the time it reaches seed. EIS allows companies to raise up to £24 million over their lifetime and to be trading for up to seven years, which is why it tends to be the scheme in play at this stage.