The term "below the line" or "Below the Line Marketing" usually means any promotional activity that does not involve paid use of the media i.e. in other words it is not media advertising.

BTL is a common technique used for touch and feel products.

For example, "below the line" promotional activities include the use of various "point of sale" or in-store sales promotions, the production and use of promotional literature and leaflets, or the attendance at trade exhibitions, shows or events. Example: Levi's use of outdoor promotional activities, videos plus window and in-store promotions

BTL Sample

Packaging

P.O.P. (Point of purchase)

A place where sales are made. On a macro-level, a point of purchase may be a mall, market or city. On a micro-level, retailers consider a point of purchase to be the area surrounding the counter where customers pay. Also known as "point of sale".

Leaflet

Direct Mail

Definition of Direct Mail: advertising sent directly to prospective customers via the mail

Direct mail is a way of advertising in which advertisers mail printed ads, letters or other solicitations to large groups of consumers. Bulk-mail rates are used to lower the cost of the mailing, and targeted mailing lists are used to maximize potential response.

Direct mail is used in many different situations, limited primarily by the imagination of the advertiser. Stores typically use direct mail to advertise new products or to distribute coupons. Charities typically use the it to raise money or recruit volunteers. Almost any sales pitch can be made by direct mail.

Packaging
Marketing - The packaging and labels can be used by marketers to encourage potential buyers to purchase the product. Package graphic design and physical design have been important and constantly evolving phenomenon for several decades. Marketing communications and graphic design are applied to the surface of the package.

 What is packaging design? by Giles Calver