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.
PDF
PDF (Portable Document Format) is a fixed-layout document standard created by Adobe in 1993 and standardized as ISO 32000. Because a PDF renders identically on every device, operating system, and printer, it is the default format for invoices, forms, reports, and anything meant to be shared or printed.
PDF is great for sharing and printing because the layout never shifts, but it is not an image editing format — content is hard to change once the file is created. Our tools can both generate PDFs from your images (each image becomes a one-page PDF, or merge several into one multi-page PDF) and read existing PDFs back into images via pdf-to-jpg and pdf-to-png.