Web hosting is a very competitive market. There are many companies that offer cheap hosting services. Prices are low and choosing the best hosting company is not an easy task. Of course, the price should not be the primary criteria. You need reliability and support at first place. But even when you have such high standards you can find many providers that offer high reliability, have great support via forums, email and telephone and offer competitive prices. Many offer also the so called “unlimited” shared hosting. You can host as many domains as you would like, you can use unlimited disk space and unlimited bandwidth. All of this for a small monthly fee. Too good to be true?
It is true if you understand the physical limitations. You will still be able to host many domains and use quite a lot of disk space, but at some point you will reach physical limitations of the web server. Web server is a computer, a machine with limited resources. And those resources are shared among many websites, not just yours. This means that you have to understand that there are some limits but in most cases your hosting will not be limited.
The number of domains you will be able to host is pretty high. This number itself is limited by the physical size of the server disk and the number of processes you will be able to run simultaneously. In general this is not a problem. If you will use static HTML web pages then this will not be a problem at all. Even if you will use scripts like WordPress or Joomla you will still be able to hosts many websites.
The problem you will encounter are the processes which run when a visitor requests a web page. Their number is very likely limited. It means that at any given moment there can be only a specified number of requests for your websites. You can host few hundred domains but only, for example, 25 websites can be accessed simultaneously. In general this is not a problem because each process lasts for only a short period of time. The number of processes is limited because there are also other users that have websites on this server and each user expects some responsiveness of the web server. Of course, this applies only to shared hosting. If you are using a dedicated server then you can use all of the available resources.
The conclusion is that “unlimited hosting” really means hosting of quite a lot of websites. If you will run standard websites which will not have heavy traffic you will never have problems with any limitation.