VAK stands for Visual-Auditory-Kinesthetic Theory.

This is probably the theory of learning styles that you are most familiar with already. The theory states that people have a preferred mode of input for material that they want to remember. 

Some remember best when they see or read something.  Pictures, graphs, maps, graphics, diagrams and so forth are very meaningful to them, and when they recall things they generally do so visually.  These so-called visual learners like to see what they are trying to learn. 

Auditory learners prefer to hear things.  They listen to lectures, learn through music, use mnemonics and similar strategies.  Auditory learners are also likely to benefit from discussions and similar settings. 

Kinesthetic learners prefer to move around and manipulate things.  These students usually like concrete items to use when learning, like flashcards or playing games.  Kinesthetic learners are the ones who learn best with a hands-on approach and often enjoy experiments and similar activities.

VAK Theory indicates that students learn most efficiently through one of the main sensory avenues. 

If a visual learner needs to memorize material, he or she would be better off reading about it or looking at pictures.  An auditory learner will learn most easily by listening, talking or even singing about the material.  A kinesthetic learner prefers to write things down, move flashcards around, or try something out.  

The movie below summarizes things very nicely.