A eukaryote is any organism whose cells have a nucleus enclosed within membranes. Eukaryotes belong to the domain Eukaryota or Eukarya. Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus, and in addition, some cells of plants and algae contain chloroplasts. Unlike unicellular archaea and bacteria, eukaryotes may also be multicellular and include organisms consisting of many cell types forming different kinds of tissue.

As the progenitors of evolution, eukaryotes will forever sit on the throne of life’s kingdom. They’re responsible for the birth of all complex life on Earth, including plants, animals, and us humans.

At one point in our planet’s history, only two domains of life existed: bacteria and archaea. And in one unlikely and incredible moment, archaea and bacteria shared genes, and this union formed the first eukaryotes. Basically, it was the most game-changing evolution to take place on Earth. On a philosophical level, they’re basically responsible for everything from the stegosaurus to Shakespeare.

And on a superzoom level, eukaryotes are characterized by elaborate, multicellular structures, possessing a nucleus enclosed within membranes.