One of the first things you'll learn when training in any form of MMA discipline is how to defend against or perform takedowns, otherwise you'll be dragged down and submitted within seconds.
Here are some of most basic takedowns you should learn and defend against as a beginner in MMA.
7 MMA Takedown Techniques
8 Simple and Effective Takedowns
Wrestling for MMA: Stance & Entry for Takedowns
Clinch Takedowns AGAINST STRONGER opponents - by UFC Lightweight Jake Matthews
5 Highly Effective Entries to Takedowns for MMA with Undefeated Aussie UFC Star Alex Volkanovski
42 Takedown Techniques in Just 6 Minutes BJJ Grappling - Jason Scully
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Wrestling Basics with Jordan Burroughs - Takedowns