What's a web host?
In order to be a good webhost, you simply need to have a server that is always online... something that is more easily said than done.
If you manage to have a web server that is always online, you will be able to let other people with internet access access the files on it at any moment they wish.
You can have your own computer running your websites, or you can pay a monthly fee to a hosting company, which has it's own datacenter full of servers.
The bad thing about a shared hosting environment, is that you are sharing resources with a lot of other people, which makes your sites and your email service slower in general.
Also, you are limited to the amount of space the hosting company assigns to your accounts, which may affect the way you wish to build offers and packages for your customers.
On the other hand, with a shared hosting service you don't have to worry about giving administering or giving maintenance to the server, or upgrading their services. This is usually done by the personnel at the data center.
If you have a dedicated web server, you have to administer it yourself, as well as keep it up to date with any new applications you need, or any configurations that are necessary as time goes by.
Although the internet is available to almost anyone on the planet, not a lot of people have their own websites. This is why web hosting is lately becoming such a growing bussiness, since it's basically like renting an apartment that only exists online.
If you are interested in starting a web hosting business, there are many sources in the internet where you can inform yourself, either in shared web hosting, or by purchasing a dedicated server.