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.
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.
WebP
WebP is a modern image format developed by Google that supports both lossy and lossless compression, along with transparency and animation. At comparable visual quality it usually produces noticeably smaller files than JPG or PNG.
Every current browser supports WebP, which makes it an excellent default for web delivery. Outside the browser the picture is mixed: older desktop software, some email clients, and legacy systems may fail to open it. If a recipient cannot view a WebP file, convert it to JPG for photos or to PNG when transparency must be preserved.