Technically juggling is when you are using 3 or more objects. However, you can amaze audiences with manipulation of just 1 item - a term called 'Contact juggling'. This is where you roll, throw or bounce the item around the place.
We are here focusing on 3 ball juggling, considered fundamental for any juggler. We will touch upon 5 ball and higher number juggling.
Equipment
Examples to use could be bought jugging balls (common to find starter 3 ball sets for only a pound), bean bags (they have the advantage of not rolling away as much), tennis balls (i used), Oranges and apples are excellent, though they don't have a high life expectancy.
You can even make some balls/bags. the key to this is not to make them too light. Socks and scrumpled paper are bad on their own. Fill socks with lentils or small nuts just enough for the size equivalent of a 3 fingered fist. seal the 'fist' by sewing or with a good number of staples and cut off the rest of the sock.
You will find it harder to juggle balls less than 5cm in diameter and bigger than your fist size.
Pre - 3 Ball Juggling
Start by playing around throwing one ball up and down, under your other arm, under your leg. Do this for 5 minutes.
Now 2 balls. You need to get used to this before attempting 3 balls, for when you get 2 balls well you are essentially doing little sections of 3 ball juggling.
Aim to throw the balls the height of the top of your head or just above that. The higher you throw, the more time that you have to catch the balls, but the less stability you will have and better technique you will need to continue juggling.
When catching a ball your arms will be more or less parallel to the ground (Mine go slightly higher than that) and you use a bit of spring in your arm bringing it up again to throw the ball again. Beginners often keep their arms too rigid and don't allow enough fluid springiness to aid their catch and throw.
2 balls. take one in each hand. We'll start with the right hand throw. Throw the ball up aiming to land in your left hand. Watch the ball and not your hands. Just when it starts to come down from its flight path, start to throw the ball in your left hand, towards your right hand. On this throw, you must throw it underneath the first ball, so that they don't collide. (See illustration above)
Joe the Juggler - good name, and good explanation on how to juggle. I recommend you take it with a pinch of salt, and don't take all the advice as gold, for i disagree with a couple of points.
http://www.joethejuggler.com/Quito/3Ball/3Ball.html
YoYoGuy - Nice short explanation of 3 ball juggling with many diagrams. http://www.yoyoguy.com/info/ball/index2.html
Chris Seguin - An old site. No explanation, but contains a great animation on 3 ball juggling if you have the right java installed (i.e.You probably have).
http://www.acm.uiuc.edu/webmonkeys/juggling/
Steve Glimpse - No explanation, but a great animation on 3 ball and also one on 4 ball juggling
http://www.frontiernet.net/~steve_glimpse/juggle.html
3 Ball Juggling
Once you have practiced with 2 balls, starting with one hand and then the other, you can start to link them. You will have to now get used to holding 2 balls in one hand and 1 in the other.
To hold the two balls, most people tend to hold one (The one they are going to first throw) more in front than the other. I do this now, though i personally found it easier when starting, to hold them side by side.
I found it good to learn by counting how many catches i achieved. I'd go for 2 catches, then 3, then 4 etc. When you get to around 5 catches, you'll take off suddenly and do 10 to 20 catches. When this happens, you are entitled to beam out a rather smug impression to any others in the room.
