A web hosting service lets people or organizations publish content on their own part of the internet. The web hosting service provider charges a, usually, monthly fee or show some ads on each page to finance its activity. The web pages are stored on computers called servers. A server is essentially a larger and more robust computer than you ordinary desktop PC. Web hosting services usually have large amount of servers to handle the load of serving all its customers content to the general public.
A web hosting service is something you look for after you have set up your broadband or dial up connection to the internet. You will need an internet connection to hand over your content to the web hosting service. Your content will mostly be HTML-files, but you can publish anything that can be distributed digitally. A good sign of quality in a web hosting provider is that tyhey provide lots of information to help you publish your content, even before you pay for their services.
The potentially dynamic content published on a web site is reached by entering a URL into the address field of a web browser such as Internet Explorer of Mozilla Firefox. The URL is a unique resource locator and as such a given URL will always point to the same content. There are exceptions to this rule, but at least it is the owner of the URL that decides what content to show for each URL. It is up to the web browser to render the published content in a way that makes sense for the current user.
The first part of a URL, the part that usually is a company name, is called the domain name. To have nice looking URL's you need to purchase the domain name you want before you engage a web hosting service provider. Most web hosts also sell domain names so you might buy your own domain name as part of the sign up process at the hosting service.
For your web browser to find the server that hosts the pages you want to see, it uses a network of servers around the world to look up the domain part of the URL. This network is called the DNS. When you buy a domain name it has to be propagated trough all of the DNS servers spanning the globe. That might take a couple of days, so don't be afraid if your site is not visible to you immediately.
The web hosting provider will serve web pages 24 hours a day all year round. It is of vital interest to you to find out how often and for how long the web service provider may go offline. Many web hosts provide an "uptime" guarantee of 98-99%.
A major problem with cheap web hosting services is that they oversell their capacity. Even the expensive web hosts oversell but not as much. They get away with this because they count on the fact that a very small part of their customers are going to have popular sites and or a lot of space demanding content.