SVG describes images as math (paths, shapes, fills) instead of pixels. The result scales to any size without losing sharpness, perfect for logos, icons, and UI graphics. SVG files are XML text, which means they can be edited in any text editor and styled with CSS. Browsers render SVG natively; for rasterized output (PNG/JPG) you can convert.
How to open
Every browser displays SVG inline. Vector editors (Illustrator, Affinity Designer, Inkscape, Figma) edit them. Any text editor can open the underlying XML.