In the early days of the internet, if you wanted to run an online service you had to buy or rent a server computer, manually install the server software for the service you wanted (often using a very unfriendly text-based interface), set it up, keep it up to date, fix any problems, watch out for security breaches etc.
This was okay if you were a computer enthusiast or a professional, but not so great for the rest of us.
Nowadays, you can just use a managed hosting company instead. They do all the technical stuff for you behind the scenes including installing, maintaining and hosting your service, while you do the actual running of the service. Managed hosting providers are like the engineering department of a ship, while you are the captain and owner on the bridge.
Because managed hosting involves labour, electricity, equipment maintenance etc, you do have to pay for it. However, it’s cheaper than you think: a social network or personal cloud start from around 5-10 euros a month in managed hosting.
You can find links to managed hosting providers on all the pages of this site discussing the kinds of online services you can create.
What happens if I want to switch managed hosting providers?
Sites and services usually operate based around a database, which stores all the articles, user accounts etc. As long as a managed hosting provider lets you export your database, you will be able to switch to another managed hosting provider seamlessly. The new provider will be able to import it and get your site up and running with them, and all your accounts, passwords, posts, followers etc will be preserved.
This is why it is crucial to ask managed hosting providers whether they allow database exports before you sign up with them. If they do allow it, that is a really good sign. Making it easy for you to leave shows they are serious about earning your trust with a good service.