What is a List?
Internet Marketing Dictionary | Lists and List Building

A list is nothing more than a list of people whose email addresses you have and to whom you can send out marketing emails. Internet marketers rely on lists to make money and one of the most effective ways to do this is to promote to your list a product as an affiliate or to promote one of your own products.

The only way to build a list sensibly online is to use an autoresponder and generally you'll find that marketers use Aweber, GetResponse, Email Aces or 1ShoppingCart. These autoresponders help you comply with CAN-SPAM regulations which is something you must do.

You get people onto your list by getting them to complete a form. There's one on this page for example. But people won't sign up to a list unless they feel comfortable that their contact details will be treated with respect, that they can unsubscribe from a list easily and that they will get something of use from being on the list in the first place.

Once you have a list you are in a very strong position to make money and there is usually a fairly straightforward mathematical link between the size of your list and how much money you can make. As a guideline, having a list of 10,000 is often enough to make a good living from - particularly if you live in a low cost country. Having said that some people struggle to make any money from huge lists. Other internet marketers make a lot of money from small lists. One factor that effects how profitable a list is will be the subject matter it relates to.  A list related to high value content will make more money than one about low value content.

If your list of 1000 people makes you $400 a month then very broadly, if you can grow your list of 10,000 people you could make $4000 a month.

One mistake people make when list building is to be too cautious with how much they are prepared to spend on promoting the list using AdWords or other PPC systems. What matters is the lifetime value of someone on your list. If it costs you $10 to get a new subscriber and an average subscriber makes you $1 a month then provided you don't have too many unsubscriptions, you will make a profit. However you need to measure response rates to your emails carefully.