Check out example codes for "how to make a circle in html". It will help you in understanding the concepts better.

Code Example 1

#circle {
      width: 100px;
      height: 100px;
      background: red;
      border-radius: 50%
    }

Code Example 2

<svg xmlns="http://www.w3.org/2000/svg">
    <circle cx="50" cy="50" r="50" fill="red" />
</svg>

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