TITLE: What is the usefulness of matrices?
QUESTION [53 upvotes]: I have matrices for my syllabus but I don't know where they find their use. I even asked my teacher but she also has no answer. Can anyone please tell me where they are used?
And please also give me an example of how they are used?

REPLY [5 votes]: I never fully got matrices until I left university. I am glad I understand now. 
An example:
A good quality camera will save the captured image uncorrected, along with a 3x3 colour correction matrix. Your computer will multiply this with the colour correction matrix of your display, and then by every pixel in the image before putting it on your display. The computer will use a different display matrix for the printer (as it is a different display).
Look at several real world examples. Experiment with colour or 2D/3D transformations, they are fun and visual (if you are a visual person). 2D is easiest and most visual.