Multiple Domain Hosting offers you to buy a single hosting plan and to divide up your apportioned hard drive and bandwidth into parts that could be assigned to other domains. This allows you to pay for a single hosting plan but to host multiple web sites. How many domains and web sites you will be allowed to have with your multiple hosting account depends on the particular hosting plan. Speaking of multiple domains an additional caution is needed. Some hosts refer to multiple domain hosting as a possibility to have multiple domains all pointing to the same web site. This is used primarily to increase web site traffic. This practice can be harmful as search engines may penalize you for doing so. In order to avoid misunderstandings you should be completely sure what specific host means by 'multiple domain hosting' before making final decision.
By hosting multiple domains we understand the ability to have many domains hosted with one web hosting account.Generally you don't purchase a website you purchase a hosting account. In some cases this hosting account can only be used to host a single domain and hence a single website. In others the account can be used to host multiple domains and hence multiple websites.
There are of course both advantages and disadvantages of hosting several domains on a single hosting account.
The main advantage is, of course, the cost. Because domains are much cheaper than website hosting accounts choosing an account that offer multiple domain hosting is a far cheaper way of hosting multiple websites than purchasing a hosting account for each website.