What is it? Why do I need it?

What it is. They're companies that have space on multiple Servers with multiple hard drives somewhere with multiple T1 or D3 lines for throughput. Their services are usually redundant, so that if your content on one server goes down, it is brought back up ASAP on a backup server so downtime is minimal. Most Hosts guarantee 99.9% uptime, which still equates to almost 4 days a year your site could be down. I have never had that experience.

Why you need it. If you have a website, you need it. You could host it on your own server, but then your uptime is subject to your ISPs uptime and if your service goes down, so does your website. If you're out of town, it's down until you return. It also means you should have a T1 line, heavy duty Firewalls, etc. Not a good option. Most Hosting Cos monitor servers 24/7/365.

Server Types: (these are simple explanations)

• Shared Hosting: Least expensive and fine for a starter or low traffic site.  $4.95 to $35 a month - Can have lots of apps installed with a few clicks, like WordPress, Joomla, Drupal, Forums, etc.
   
• VPS: Virtual Servers- Like a shared, sort of, but much fewer clients on one server with a lot more bandwidth and fewer dropped surfers at high traffic. $35 - $250/month  Some have lots of apps installed with a few clicks, like WordPress, Joomla, Drupal, Forums, etc. Some just bare hosting space waiting for your content.
   
• Dedicated Servers: No normally many extras, requires you to have or hire experts to configure.

• GoDaddy great pricing- has some quirks- has all types - I have 2 shared Hosting accounts with them and multiple domains. Tech support not real good. (my experience)
   
• Host Gator excellent pricing- Excellent reviews- I'm setting up a couple of sites here soon. High tech support ratings.
   
• BlueHost similar reviews and only one pricing. Get crappy reviews on tech support.
   
• ViaVerio  good to high pricing, no auto install features, limited control panel, excellent support, great server uptime (I have had two VPS Servers with them for 6 years with high traffic (30,000-70,000 visors a month for one domain) and no dropped incoming visitors. No frills.