|A football oval with the playing positions listed|
Players are allowed to tackle the player that is in possession of the ball. If the player that is tackled does not handpass or kick the ball before getting pulled to the ground a free kick is awarded to the opposing team. If the player getting tackled drops or throws the ball a free kick is awarded. Although tackles are allowed, tackles that are considered too high (grabbing around the neck or head) are against the rules and a free kick will be awarded to the player that was tackled. Pushing in the back is also against the rules but a clean tackle from behind is fine though.
For more info check the Wikipedia pages:
Here are the highlights from the Grand Final, Only the 3rd time a Grand Final has ever drawn. My team is Collingwood (the Magpies, in black and white stripes):