Short answers, pulled from the story.
A cell is the basic structural and functional unit of all forms of life. It consists of a semipermeable cell membrane enclosing cytoplasm that contains genetic material. The term comes from the Latin word cellula, meaning small room.
Robert Hooke discovered cells in 1665 while examining a thin slice of cork under an early microscope. He named them after their resemblance to the cells in a monastery, using the Latin word cellula.
Prokaryotes lack a membrane-bound nucleus and keep their DNA in a region called the nucleoid, while eukaryotes enclose their nucleus in a nuclear membrane. Prokaryotes are always single-celled, but eukaryotes can be single-celled or multicellular. A eukaryotic cell can be 2 to 100 times larger in diameter than a typical prokaryotic cell.
Cell theory states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function, and that all cells come from pre-existing cells. It was developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann.
Cells emerged on Earth around 4 billion years ago. The first cells were most likely heterotrophs, and eukaryotic cells arose some 2.2 billion years ago through a process called eukaryogenesis.
The estimated cell count in a typical adult human body is around 30 trillion cells, with 36 trillion in an adult male and 28 trillion in a female. There are an estimated 200 different cell types in the human body.