I've finished html fundamental cource but never seen those(following description's) attributrs and elements before. Wht r they?

Question

<svg width="500" height="130">

<defs>
<linearGradient id="grad1" x1="0%"y1="0%"
x2="100%" y2="0%">

<stop offset="0%" style="stop-color:rgb(255,0,0); stop-opacity:1" />

<stop offset="100%" style="stop-color:rgb(255,0,0); stop-opacity:1" />
</linearGradient>

</defs>

<ellipse cx="100" cy="70" rx="85" ry="55" fill="url(#grad1)" />

<text fill="#ffffff" font-size="45"
font-family="verdana" x="50" y="86">SVG</text>

sorry, your browser does not support inline SVG
</svg>

Answer 1

https://www.w3schools.com/graphics/svg_intro.asp

Answer 2

The <defs> tag is short for definitions and contains definition of special elements (such as gradients) like linear gradients
<svg> is an tag which used to plot graphical contents like circle ellipse ect
And your code is make an ellispse with describe redius fill is used to color the ellipse