Argentine Tango is essentially walking with a partner to the music. Dancers keep their feet close to the floor as they walk, with the ankles and knees brushing as one leg passes the other. The Tango embrace can vary from very close (lady on the man’s shoulder) to open (at arms length).
Argentine Tango has certain patterns of movement or moves which are taught by instructors but improvisation is the key element of this social dance. This places an importance on a clear signal from the leader and good understanding of leads by the follower.
The connection between leader and follower is paramount. One of the few constants across all Argentine tango styles, is that the follower will usually be led to alternate feet, and the follower rarely has her weight on both feet at the same time.
For an example of Argentine Tango, see the video below: