I wanted to know what 1A yoyoing is. Is it certian tricks plz tell mee
1a is the yoyoing style with only one sleeping yoyo. You do 1a tricks.
Addition: Here is the list of the Styles of Play.
1A is the most common style of yoyoing you hear of.
It is a single yoyo doing string tricks.
Read that forall the styles.
1A Yo-Yoing is in the learn section, and it is every trick up to the section that says Looping Basics.
It is mostly what you see for Yo-Yoing, but that is my view. 
Correction. There are actually more than 5 styles of play. Just 5 main styles used for Contests.
1A yoyoing is a type of yoyo play, where you have one yoyo attached to a string, with the string tied around your finger. The reason I said that about the string is because there is a type where the yoyo is not attached to the string, which is 4A, or OS(Offstring). There is also a type called 5A where you have a counterweight on the end of the string instead of it being tied to your hand. Back to topic. Some 1A tricks include Split the Atom, or another, like trapeze. Most of the tricks on here are 1A. There is a section under Learn for offstring. Here is a link for ALL the types of yoyo play, if you need more information: http://yoyowiki.org/wiki/Styles_Of_Play
Correct, but you can use different styles (Such as 9A) to compete in 5A.
Ryan Lai doing 9A at worlds:
http://www.youtube.com/watch?v=ZcU3lNWaR1c
Also, there is AP (Artistic Performance) when it is not about the tricks, but about the performance. Here is John Higby as 2008 world AP champion: