A common question is: "My ISP has given me 10 MB of disk space; why can't I host my website there?"
The simplest answer is: "You can - up to a point". If all you need is a simple website for yourself or your family, this is not a bad option, particularly as it comes free with your monthly subscription. You will also get an email box or two. There are, however, a few limitations.
Firstly, the site name, or URL (Uniform Resource Locator) will be a sub-domain of your ISP. This might be perfectly suitable for "mary_jones.aol.com", but not for "microsoft.aol.com". Your site name is attached to the front of the ISP's address, and visitors might perceive your company as being a subsidiary of AOL. If you want your own unique domain name, you cannot have it hosted on an ISP's web server for free.
Secondly, there will only be limited disk space available, and little opportunity to add the kind of programmable functions which are part of most websites today (for the techies this means facilities like CGI, PhP, ASP, mail groups, autoresponders etc.)
Another common question is: "I have broadband - why can't I host my domain myself, at home or in my office?"
The answer this time is: "Well, you can, but again there are some major drawbacks."
Firstly, broadband connections are almost always asymmetric, which means that information is sent out at a fraction of the speed it can be received. This suits the majority of users, who can browse the web and download files or pictures at the highest possible speed. They actually upload, or send out, very little data other than page requests.
With the fastest connection currently available (2Mbs), it is just possible to host a server yourself provided there are only a relatively small number of "hits" each day, and this will improve as faster speeds become available. Bear in mind however, that you do not have sole access to that 2Mbs! Each connection is shared amongst a number of users in your locality, such that at any one time you should obtain at least a reasonable speed. At busy times your share of the line could drop to a few Kbs, and a busy web server would just kill the line speed for everyone.
Secondly, installing a web server (and keeping it running well) is not a task for the faint hearted. There are many issues to be taken into consideration, which are far beyond the scope of most users. Keeping valuable data secure, avoiding viruses and web attacks, making regular backups and maintaining the hardware are just a few of the problems.
A professional hosting company will possibly look after hundreds of servers in an air-conditioned, secure environment and many of these tasks will be automated. By this means they are able to save you a great deal of work and hassle at very competitive prices.