unlimited domain names

What is the reason of hosting multiple domain names under one account?
I have seen that many companies offer that but can't understand that.
Any ideas?

I would assume, just simply incentive to keep all your hosting with that one company.

DanKo - I have owned multiple domains for quite some time now. A few years ago, I was still with GoDaddy and I felt that combining all of my domains into one account was optimal. If I had a different account login for every domain I owned, I'd have trouble keeping up with them. Resellers would have an even worse time tracking all of theirs.

Actually the benefit of doing this is so that you only have to pay for one account. All of the sites you have hosted on that account will pull resources from that account. No point in having to pay 5x $3.99 a month for 5 hosting accounts when none of your 5 sites may use all the resources available in just one account. So you put all in one account and pull off those resources.

Saves you money and easier to remember your login!

It is save your cost for hosting some websites.
But there are the limit of the multiple domain name in one hosting as
- The number of inodes
- The resource (cpu/ram) usage
- ...

Its a no brainer really.

If you have one domain with one hosting account, then you incur a hosting cost for each one.

Multiple domain names with multiple hosting account capability, such as a Reseller Hosting account (hostgator.com / surpasshosting.com) allows you to have as many websites on these domain names as you wish, all for the agreed fixed monthly cost.

clearly, this is very cost effective IF you have more than half a dozen domain names you wish to place a website on.

In my opinion you have no reason to maintain a lot of domains. You can sign up just for one account. You pay 3.95USD or 4.95USD depending of the company.

i think it is more economical to keep all your domain names under one account

It is definitely easier to have all the domains under one hosting account. However, if there is any sort of outage at your web host company, then all of your sites will be down. A good strategy might be to spread your sites across several hosting companies so that not all your sites will be down in the event of an outage. (And outages do come, no matter what the hosting company claims on their site.>!!)

Also, another thing to think about: If you have one hosting account with the same username/password for all domains--it is possible that a hacker could get access to all of your websites if they hack your username/password. Happened to me. Wasn't pretty. I now have my sites spread out across multiple hostng companies. Cost a little more, but well worth the peace of mind.