Since 2009, FatCow has been committed to purchasing Renewable Energy Certificates (RECs) to offset its use of electricity; this year, the company will purchase enough RECs to offset its use of electricity by 200%. FatCow's commitment to the environment will prevent 999 metric tons of carbon dioxide from being released into the atmosphere, this year alone; that's equivalent to planting 213 acres of trees or taking 196 cars off the road!
Shared hosting is like an apartment building where the building or server has many tenants or hosting accounts sharing the space and the utilities. This works just fine if you have a small family but if everyone in the building has ten roommates move in who are constantly running the water and using the wifi then the water pressure and wifi speed start to suffer. The key to shared hosting is that it is meant for small business websites, sure you can pack the roommates or files in like sardines but it will really be uncomfortable.
Many services offer so-called unlimited or unmetered service for whatever amount of bandwidth, disk storage and sites you use. It's important to understand that most terms of service actually do limit the definition of "unlimited" to what's considered reasonable use. The bottom line is simple: if you're building a pretty basic website, unlimited means you don't need to worry. But if you're trying to do something excessive (or illegal, immoral or fattening), the fine print in the terms of service will trigger, and you'll either be asked to spend more or go elsewhere.