What’s the difference between active dry yeast and instant yeast? And what is fresh yeast?

Active dry yeast (ADY) and instant yeast

(also called bread or rapid-rise yeast) are two forms of baker’s yeast. They can be used interchangeably. ADY is typically activated or “proofed” in warm water prior to being used, though some professionals say that these days ADY is more reliable and can be added directly to dry ingredients. We recommend following your recipe. Instant yeast doesn’t have to be proofed and can be added directly into recipe ingredients. Instant yeast granules are smaller than ADY granules; therefore, they dissolve and rise faster than ADY. Cake, compressed, or fresh baker’s yeast is soft and crumbly and requires no proofing, but its highly perishable. We prefer instant yeast for its potency (similar to fresh) with ADY-like convenience.