At a high level, online video works through a chain of creation → delivery → decoding → display. Here’s how that process unfolds in clear steps.
1. How video is prepared for the internet
a) Capturing the video
A camera (or screen recorder) captures images many times per second (frames), along with audio.
b) Compression (encoding)
Raw video files are enormous, so they are compressed using video codecs such as:
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H.264 / AVC
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H.265 / HEVC
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VP9
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AV1
These codecs remove redundant visual data and store only changes between frames. The result is a much smaller file that still looks smooth.
c) Packaging for streaming
The compressed video is split into short segments (usually a few seconds long) and packaged using formats like:
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MP4
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WebM
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HLS (HTTP Live Streaming)
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DASH
This allows the video to adapt to your internet speed.
2. How the video travels across the internet
When you click “play”:
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Your computer sends a request to a server (often a content delivery network, or CDN).
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The server sends small chunks of video data over the internet using standard web protocols (HTTPS).
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These chunks arrive continuously, not all at once.
This is why you can start watching before the entire video is downloaded.
3. How your computer receives and understands the video
a) Buffering
Your computer temporarily stores a few seconds of video in memory (RAM). This buffer smooths playback if the internet connection briefly slows.
b) Decoding
The compressed video data is decoded back into raw frames. This is done by:
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Your CPU, or
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Your GPU (much faster and more efficient)
Modern systems almost always use hardware decoding via the graphics card.
4. How the video is displayed on your screen
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Each decoded frame becomes a grid of pixels.
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The GPU converts these pixels into electrical signals.
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Your monitor receives the signal and refreshes the image (typically 60–144 times per second).
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The images appear in rapid sequence, creating smooth motion.
Audio is decoded alongside the video and sent to your speakers or headphones in sync.
5. How you view video on your computer
a) Using a web browser
When you use a browser (Chrome, Firefox, Edge, etc.):
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The browser contains built-in video players and codecs.
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HTML5 video handles streaming, buffering, and synchronisation.
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JavaScript controls playback (play, pause, seek).
You don’t usually need extra software anymore.
b) Using apps or media players
Some services use dedicated apps (or players like VLC). These do the same job as a browser but with their own decoding and interface.
6. Why internet speed and hardware matter
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Slow internet → more buffering, lower resolution
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Faster internet → higher resolution (HD, 4K)
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Weak hardware → dropped frames or stuttering
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Modern GPU → smooth playback with low power use
Adaptive streaming automatically lowers or raises video quality to match your connection.
In short
Online video is compressed, chopped into pieces, sent across the internet, decoded by your computer, and rapidly drawn to your screen by the graphics system. All of this happens dozens of times every second, fast enough that it feels instant.
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