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What is the difference between rgb() and rgba()? What does the alpha channel do?

CSSJunior~1 min read
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rgb() sets a color through three components: red, green, and blue. Example:

css
color: rgb(255, 0, 0);

rgba() adds a fourth parameter, the alpha channel, which controls transparency:

css
color: rgba(255, 0, 0, 0.5);

The alpha channel accepts a value from 0 to 1:

  • 1, a fully opaque color
  • 0, fully transparent
  • 0.5, semi-transparent

The difference: rgb(), without transparency, rgba(), with the ability to specify it.

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What is the difference between rgb() and rgba()? What does the alpha channel do?: CSS Interview Question