Lots of people just know tai chi is a form style exercise, in fact, push hand is also a core part of tai chi.
What is pushing hand? below are some videos of pushing hand, believe that you will figure out the charm of it after watching.
Tai Chi Push Hand Tounament 2015 80KG Elimination
https://www.youtube.com/watch?v=PIaS99pmjxY
Hong Kong Tai Chi Push Hand Tounament 80KG Final 1ST round
https://www.youtube.com/watch?v=4fdrSCr20vs
Hong Kong Tai Chi Push Hand Tounament 2015 80KG Final Round
https://www.youtube.com/watch?v=BbB1aYsx6AU
https://www.youtube.com/watch?v=ptNl4S9ph_0
2016 Tai Chi Push Hand Championship Final
https://www.youtube.com/watch?v=igZ_12YSSro