it is building a list of email subscribers for future marketing. you send email newsletter to your subscribers at a later date. how to do it? you add a subscribe option on your site. visit my site and look at the left sidebar
List building is the process of adding new subscribers to your mailing list. The subscribers give you their email address in exchange for receiving certain information, such as a special offer or a free gift. List building is an ongoing process, you should be very patient and never stop building your list. This article can guild you to build a high-quality email list: http://emailmarketing.comm100.com/email-marketing-ebook/build-email-list.aspx
@ Sabrina-Gage You have given a good link to know how to build mailing lists for Email Marketing campaigns.
What you do is that you keep on managing User lists in a DB or some spreadsheet with desire info.This will helps you to send them regular newsletter,new offers and even helpful in remarketing a lot.
You can get subscribers from your blog as well, try to give something in free and visitors would subscribe, this way you can collect the email list.
The key to list building is giving a freebie. You can give a free report or an eBook that helps users with an issue or gives them additional information. Once they sign up to your list, you need to engage them from time to time and build a relationship with them through helpful/valuable information you share through the newsletters. Doing so helps build trust, making it easier for you to recommend products to them. Hope that helps. Have a good day!