I have always payed a company to host on dedicated servers which is really expensive, 1 of my sites has 2 servers right now, a web/http server and a seperate mysql server.
What would it take for me to do this from home?
I would need a LAMP setup. 1 benefit I can see is I could add as much ram and stuff as I wanted
I only have a cable internet connection, would that be bad on a high traffic site?
Technically, unless your cable provider is blocking access to the ports that you want to serve (probably 80 and 443 for http/https respectively) then there's nothing stopping you from hosting your own . Seth said as much.
As pretty much everyone else said, it's a bad idea.
So what would it take to make it a good idea?
Well, first, know that you're never going to get as fault tolerant as the expensive colocation facilities. That's why they're expensive. They have things like redundant power sources, redundant generators, redundant network connection, redundant everything. You can't afford this.
Instead, a close approximation might be...
A home with a section of the basement dedicated to the servers. Get a cheap four post rack, and buy rack mount servers. You can buy 2nd hand or from cheaper places like Supermicro, etc
Get a decent quality UPS, and make sure it's enough to power the servers and network equipment for 15 minutes or so.
Get a leased line for bandwidth. This is the expensive part. A cable modem that gets you 10Mb/s down and 2Mb/s up might cost $50 a month. A T1 that gives you 1.5Mb/s down and 1.5Mb/s up will probably run you $700 a month, if you can find a provider who will install it in your house. Depending on the area, you might be able to find metro ethernet for $1500 that gives you 10Mb/s both directions.
Buy environmental sensors to track the temperature and humidity of the area around your servers. Homes aren't meant for this sort of thing, so you have things like waterlines above servers that can break and dryer vents which cause moisture and heat. Sensors will help you maintain a good working environment.
Get insurance. The kind of insurance will depend on if it's a business. Here's a hint: create a business.
The down side? To deduct it from your tax, you've got to make that much first.
Until you have a business, and your business insurance covers it, make sure your home/rental insurance covers them.
Self-hosting is fine for personal projects (and easy to do, just make sure your server is in a DMZ away from computers that you care about).
If you're talking about something that needs to be Up, then don't do it from home. Off the top of my head, you will run into these problems:
ISPs (especially Cable ISPs) don't like their customers running web servers out of their house. You might not be able to serve anything out of the privileged ports, because your ISP has blocked them to keep you "safe"
Your home upload speed is really small
Your home is not redundant
You have to pay for the electricity and cooling, which doesn't sound like much, but will add up after you set up a couple of 24x7 boxes.
Even if everything else is fine, your reverse DNS will show up as "cable-customer.ABC123.your-isp.net", so any mail you send will be marked as spam, and may trigger other anti-spam measures.
You might get around some of the ISP problems by getting a "pro" plan with a static IP address or something.
It's not difficult. The question is whether or not it is adequate for your needs.
I can't even begin to touch what you would need, as you've provided no info about the site you wish to host. A simple static site, even with relatively high traffic, can be hosted just fine off an old 386. A highly dynamic site may need server-grade hardware even under low load.
Most consumer grade Internet connections are asynchronous. That is to say they can download more than they can upload. If you host a site, you're sending traffic the wrong way. You could very easily max out your upstream connection without trying. I imagine it's probably something in the region of 512Kbit/s. There is also a chance that this is contented with other people in your neighbourhood, so during peak usage, you might only see 100-10kbit/s. A hosting provider will usually have in excess of 100mbit/s.
A hosting provider also make sure that you have continuous power, air conditioning and networking. They do this by making sure as much as possible is redundant. If one of their transit connections fails, they'll have several others that can replace it, usually within seconds. If your cable modem fails, you need to wait until it's fixed before getting back online. Your hosting provider probably has SLAs with their suppliers. You probably have no SLA, so you can't claim any money back from your connection provider.
I host a number of things from my DSL connection, but these are only things that I use myself. Anything that's meant for the public to see, I host on a dedicated server in a colo facility. There is nothing stopping you from hosting sites in your house, but you need to appreciate that you wont have the bandwidth or the reliability that a hosting provider will give you.
