But from that post:
Hope that helps you in your quest.LCD, Plasma and OLED screens are all fixed resolution devices. Their screens are made up of hundreds of thousands of tiny squares, each of which can change colour to become part of a larger image. For the image to look sharp and clear, it needs to be the same resolution as the screen, meaning it has to be made up of the same number of tiny squares. So when you give it an image which is too big or too small (Say watching an old VHS tape on a modern 1080p TV, or trying to watch a 1080p blu-ray on a 720p TV,) the image has to be stretched or squished to fit within that fixed grid of squares. The results are seldom pretty. Text especially tends to become hard to read, and everything gets a bit fuzzy.
The old fashioned Cathode Ray Tube on the other hand functions as more of a projector. A "Light gun" at the back of the 'tube hurls a pattern of electrons forward, causing little specs of phosphorus on the inside of the glass to light up and create the image. This gives it a great deal of flexibility when it comes to input resolution. So long as the resolution is lower than the number of openings in the front of the glass (Called the mask,) you'll end up with a nice looking picture. And even when the resolution exceeds that limit the results are usually okay, the image just loses fine detail. This makes a CRT monitor ideal for playing old games on, watching home movies or any number of videos which would become chunky and awful on a fancy new high definition LCD TV.