Web hosting service will allow your website to be accessible through internet. Web hosting companies provide space (usually measured in GB) and other facilities depending upon the package.
New entrants to the web space are often confused about which type of web hosting to purchase. I have even received queries from some experienced web masters.
Yes, there are some free web hosting services. But they offer very limited features. You cannot rely on these. Sometimes free web hosting is supported by annoying advertisements. This is not recommended.
In most cases, you will be looking to buy shared web space. Your website is placed on shared server where many other websites are hosted. Don't worry, they will not do any harm to your website. All domains share a common pool of resources such as CPU and RAM. This is cost-effective reliable solution for your website.
You get a lot of space to sell to other clients. In short, reseller web hosting is for people who are interested in becoming web hosts themselves.
One server is divided into many virtual servers, Resources are allocated in a manner that does not directly reflect the underlying hardware. You can have root access to your own virtual space.
You will get your own web server with full control. It can be either managed or unmanaged (self-managed). Managed servers are relatively more expensive than self-managed.