PNG
A lossless format with transparency support, designed for graphics and screen use rather than photographic delivery.
Measured in
MB
In depth
PNG compresses flat colour and sharp edges superbly and continuous-tone photographs poorly, often producing files several times larger than an equivalent JPEG. Its alpha channel makes it the standard for logos, screenshots and web graphics needing transparency, and it has no support for CMYK or for 16-bit-per-channel photographic work in most tools.
Examples in practice
A screenshot saved as PNG is smaller and sharper than as JPEG; a landscape saved as PNG is four times larger.