Before reading this page you should work through the 'Animation Basics' page which explains how to animate an object that is rigid (does not have a posable skeleton or 'armature'). It's much more interesting but rather more difficult to animate a 'rig' (a characters with a posable skeleton) which is the subject of this page.
A rig is a body attached to a skeleton or 'armature', ready to be set into different poses in an animation. We won’t have time to make a very sophisticated character because it is difficult to attach the ‘flesh’ to the bones such that the character behaves realistically set in different poses. So we'll use a ready-made rig.
I've chosen the Baker rig because the character is cute and has the potential to be very expressive - there are plenty of controls to control facial expressions although you will probably have time to do this only if you choose to work on this as the end-of-year project. The Baker rig was created by David Ward (no relation) for the excellent website cgcookie.com . There are plenty of free tutorials on that site but the Baker series is not free - you need to pay 9 Euros to become a 'citizen' before you can follow or download the series - it's good value though. See cgcookie.com/blender/cgc-series/character-course-animating-a-character.
Meet Baker in this YouTube video (1.5 mins):
You can download the Baker rig HERE (large file, 3MB). I've checked that it is compatible with Blender 2.64. I've hidden the shapes that control the face but you can unhide them by turning on the second layer in the Object Data panel (while in Pose Mode) if you need them. A problem that stopped the mouth controls from actually moving the mouth has been fixed in this file.
This wonderful rig allows you to adjust all kinds of properties such as clothes colors, skin color, hair style, hip size and breast size (thus male/female), muscle vs. fat, etc etc. It's all free on a Creative Commons license and downloadable HERE or HERE. You may need to become a member of Blendswap.com - membership is free and will give you access to thousands of great Blender files.
Here are links to some other rigs that you can download. Check them out!