Even when you know how an optical illusion works, it can be hard to convince your senses that what you're seeing isn't real. The best way to demystify an illusion isn't necessarily to read about it—sometimes, you just need to see the image from a different perspective.
These moving illusions from Lenstore use clever animations to reveal the mechanisms behind their visual trickery. The second image in the slideshow is an Ebbinghaus illusion. As the cluster of blue circles gets bigger, the red circle in the center appears to shrink, and the opposite seems to happen when the blue circles contract. Hit the Reveal button and you'll see that the red circle actually stays the same size the whole time; this is the result of relative size perception.
The third optical illusion shows four sets of lines, with the parallel lines apparently moving back and forth together. In reality, the four lines are all part of the same moving square. The trick behind this illusion is called motion binding: When two sets of objects are in motion in front of you, the movements of one set affect how you perceive the movements of the other. Your brain constructs a pattern for the line movements that doesn't exist.
Once the solutions have been revealed, you may still have trouble reconciling what you see with what you know to be true. But at the very least, turning the illusions off in the moving images below should give your brain a break.