Every digital video you watch — Netflix, a Zoom call, a YouTube clip, the ad on a billboard — is fundamentally the same thing: a fast slideshow of still images. Each image (a frame) is stored as a grid of tiny coloured squares (pixels), and the player shows enough of them per second that your eyes stitch them into smooth motion.
What makes it "digital" is that every pixel's colour is stored as a number, not as a wave on a tape or a pattern on film. Numbers can be copied without loss, sent over the internet, and compressed by clever algorithms so a two-hour movie fits on your phone instead of on a stack of hard drives.
That simplicity hides a lot of choices that drive cost and quality: how many frames per second (24, 30, 60, 120), how big each frame is (resolution), how many bits describe each pixel's colour (bit-depth), which colours the system can show at all (color-space), and how aggressively the file is compressed (codec, bitrate). The rest of this glossary is essentially a vocabulary for those choices.
