I think Information Design is a grouping of ramdom thoughts into a cohesive manner that tells a story or provides an explanation.  Of the gazillion bits of information out there, I only want to know how to tie my shoe.  The ability to collect that information in one place at one time, coherently, so I can follow the instructions has designed that information for my use. 

PS: I know how to tie my shoe however, I am using this as an example on how to explain information and the way I understand it.

Kim Baer, from the Information Design Workbook explains that Information design is information without structure is a jumble of data, words, pictures, movements and sound.  By designing that information for particular user or function, we can make all that information meaningful.  (p. 12 & 13) 

Baer, K. (2009). Information design workbook. (pp. 12-1). Beverly, MA: Rockport Publishers.