The PNG image was compressed from 6MB to 4.6MB, and the JPG version was compressed from 524 KB to 242 KB. Obviously, saving and compressing your image as JPG will save you more space on your disk.

A PNG file is a Portable Network Graphics file. The format uses lossless compression and is generally considered the replacement for the GIF image format. PNG files store graphics on websites. Some ...

PNGTree is one of the best websites for downloading PNG images with a transparent background. From simple icons to buildings, clouds, etc. – you can find almost everything on this website.

The TL;DR is that high contrast between background and text colors is important, and that for many users, black text on a white background is a) most legible and b) most professional-appearing.