Like most things, you get what you pay for with free web hosting. They may or may not provide a level of reliability, and if your web site needs to be working all the time, you need to be careful when choosing a free host.
There are a few restrictions that you'll probably have to live with when choosing a free host:
Free web hosts often put advertisements on your pages, which could even include your competitors. This is often the way free hosts recover the cost of hosting sites for nothing.
These ads can be a nuisance for your visitors, and if your website is business related in any way, they can be pretty unprofessional.
On a free web hosting plan you'll probably get either very little or no customer support. An online FAQ page could be your only source of information.
And complaining won't help - after all, it's not like you're paying for the service, right?
Using free web hosting is "penny wise but pound foolish" as the old saying goes. You might save a few bucks, but there can be lots of problems.
Frequent server failures, limited bandwidth, no scalability and thousands of sites using resources from the one free server are just a few possibilities.
You usually get a limited amount of hard drive space with a free web host, and they may limit you to certain types of files (no MP3 files for example). This can put severe limits on what you can do with your site.
You sometimes also have to use a subdomain or subdirectory on free web hosts. This means you'll have a long, hard-to-remember URL for your web site.
These are all real disadvantages to free hosting. There are millions of websites on the internet. People don't go back to sites that aren't working properly - they just find another one that does.
If you're setting up a business website, avoid free web hosts. The savings are small compared to what you could lose in customers and future business.