Inbound marketing, in its simplest form is promoting a company and/or business through a variety of forms of content marketing including but not limited to; blogs, podcasts, videos, eBooks, white papers, eNewsletters, SEO, and social media.
On the other side of the spectrum there is outbound marketing. Strategies that are considered outbound marketing are various forms of marketing through buying attention. These forms include but are not limited to; flyers, billboards, TV advertisements and cold calling.
With inbound marketing, the objective is to reel in customers with constant quality content. The idea is to earn prospects as your customers instead of "buying" them.