PNG’s are a great way to quickly enhance you videos with graphics, lower-thirds, callouts, cut-outs of people, ect…
You don’t need to spend hours in Fusion or using effects/titles in the Edit page in order to create some awesome elements.
DaVinci Resolve and Affinity Photo are a match made in Creators heaven.
DaVinci Resolve is free, and Affinity Photo is only $50, and that’s when it’s not on-sale! (NO SUBSCRIPTION!!!)
But, you could also use Photoshop, GIMP, or other image editor that allows you to output a PNG.
The reason why we use PNGs is because they support transparency. That means, essentially, no background.
There are other image formats that support transparency (like tiff) but PNG is ubiquitous and easy to create, find, and use.
You could also use a VECTOR editor like Adobe Illustrator, Affinity Designer, or Inkscape when you want to create very complex and extremely high quality transparent files for logos for example.