PNG
PNG is a lossless raster image format created in the mid-1990s as a patent-free replacement for GIF. It is the standard choice for screenshots, logos, UI graphics, and any image that needs transparency.
PNG preserves every pixel exactly and supports a full 8-bit alpha channel, so text and sharp edges stay crisp. The downside is size: photographs saved as PNG are far larger than the same image as JPG or WebP. Support is universal in browsers and editors, making it a safe default for graphics — just avoid it for large photo collections.
JPG
JPG (also written JPEG) is the most widely used lossy image format for photographs, standardized by the Joint Photographic Experts Group in 1992. Practically every camera, phone, and image application can create and open it.
Its strengths are small file sizes for photos and universal compatibility across devices, browsers, and software. The trade-offs: lossy compression introduces artifacts, there is no transparency support, and quality degrades a little more with every re-save. Use JPG for photographs; choose PNG for screenshots, logos, or anything that needs sharp edges or transparency.
SVG
SVG (Scalable Vector Graphics) is an XML-based vector format maintained by the W3C, used for logos, icons, charts, and illustrations. Instead of storing pixels it describes shapes, paths, and text, so an SVG stays perfectly sharp at any size.
For simple graphics SVG files are tiny, editable in any text editor, and styleable with CSS. It is not suited to photographs, and because SVG can embed scripts, files from untrusted sources should be sanitized before being displayed inline. When a fixed-size bitmap is required — for app stores, email, or older software — rasterize the SVG to PNG.