Digital artworks can consist of a variety of formats from photos and videos to audio and animation. An NFT creator can be deeply committed to one of these art forms or be a multifaceted NFT maker who dabbles in different NFT art formats. As obvious as it may already seem, NFT artworks do need to be digital.
If you have physical works but want to create an NFT out of them, you can digitise them. For example, take a digital photo of your paintings. Your pre NFT artworks can be run through an NFT generator software such as Appy Pie to further digitise their look before they join your NFT collection.