Drop a .psd above, get a PNG of the finished design back, transparency intact.
Photoshop files do not open in ordinary software, and Photoshop is a subscription. A designer sends a logo, an agency sends artwork, and the .psd sits there unreadable in your downloads.
PNG is the right answer when the design has transparency. Logos, badges, cut-out product shots and anything meant to sit on a coloured background need the empty areas to stay empty. JPG fills them with white; PNG keeps them.
What comes out is the flattened composite - the finished picture Photoshop stores alongside the layers so other software has something to show. That is the design as it was last saved. The layers themselves stay in the .psd.
Lossless, so nothing degrades. PNG stores every pixel exactly, which suits artwork with hard edges, flat colour and text far better than JPG does.
Size: the PNG lands far smaller than the .psd, which stores each layer separately and can run to hundreds of megabytes.
For a photograph rather than a design, PSD to JPG goes considerably smaller and the difference is hard to see.
Client artwork never leaves your machine.