Question:

Answer by Web Hosting Ratings:

Space is the amount of "stuff" you can put on your web site.  Available space is usually listed in megabytes (MB, millions of bytes).  Single letter takes up one byte.  HTML files are usually rather small (this file is about 25,000 bytes) but pictures and programs can get quite big.  Your scripts, emails and stats will also take up space on your host.
Transfer is the amount of "stuff" that visitors to your site can download before you reach your monthly limit.  Transfer is usually listed in gigabytes (billions of bytes).  After the transfer limit is reached for the month, you will need to pay extra for additional transfer at higher rates.  For example, if an average visitor to your site views 3 HTML pages of 20 KB (thousands of bytes) each and 8 small embedded pictures of 10 KB each, and you get 500 visitors per day, you will require at least (3 * 20 + 8 * 10) * 500 * 30 = 2,100,000 KB = 2.1 GB of transfer per month.