This encyclopedia deals with written science fiction in all of its forms, not only novels and short stories but also mediums often ignored in other reference books, such as plays, poems, comic books, and graphic novels. Some science fiction films, television programs, and video games are also mentioned, particularly when they are relevant to written texts. Its focus is on science fiction in the English language, though due attention is given to international authors whose works have been frequently translated into English.
Since science fiction became a recognized genre and greatly expanded in the 20th century, works published in the 20th and 21st centuries are most frequently discussed, though important earlier works are not neglected. The texts are designed to be helpful to numerous readers, ranging from students first encountering science fiction to experienced scholars in the field.