What it actually means
Openreach is the wholesale arm that looks after the cabling underneath the country. When you see an engineer in a green van digging up a pavement to pull fibre into a new estate, that is an Openreach engineer working on the shared network. They do not sell broadband to the public directly. Instead, they sell access to that network to internet service providers, who then sell packages to homes and businesses.
Most of the broadband sold in the UK runs on Openreach, including Inspire. That means the cable in the road and the box on your wall is the same whether you buy from a small independent provider or one of the household names. What changes is the company billing you, answering the phone when something breaks, and deciding how quickly an engineer is sent out. Openreach manages the physical fault on the line. The ISP manages everything you actually experience.
At home
What this looks like in the house
Most households never deal with Openreach directly, and that is by design. If your broadband drops, you call your provider, not Openreach. The frustration shows up when an ISP tells you a fault is with Openreach, then disappears, leaving you to chase updates while the kids cannot get on a Zoom lesson. The cable in the road is shared. The experience of getting it fixed is not.
In business
What this looks like at work
For a business, an Openreach engineer is sometimes the difference between a half day outage and a full week of card machines down. Most ISPs raise a fault, give you a reference number, and then sit back waiting for Openreach to update them. While that goes on, your team cannot take payments, your staff cannot work, and your phone keeps ringing with customers who think you have gone bust. Fault ownership is what costs you money, not the cable itself.