Which file extension represents graphics that support transparency and interlacing?

The file extension that represents graphics which support transparency and interlacing is .png. PNG stands for Portable Network Graphics and is widely used on the web due to its ability to handle images with transparency, allowing for smoother blending of images with various backgrounds.

One of the significant features of PNG files is their support for an alpha channel, which means they can represent varying levels of transparency rather than just solid opaque or fully transparent states. This capability is crucial for creating layered designs, logos, and images that need to blend seamlessly into different web layouts.

Additionally, PNG files can use interlacing, a method that allows the image to be progressively displayed in layers as it loads, giving users a quicker preview of the image even if the full download is not yet complete. This makes PNG a preferred choice for web graphics when quality and transparency are essential.