He laid his right hand on me, saying, “Don’t be afraid. I am the first and the last,
18and the Living one. I was dead, and behold, I am alive forever and ever. Amen. I have the keys of Death and of Hades.
20The mystery of the seven stars which you saw in my right hand, and the seven golden lamp stands is this: The seven stars are the angels of the seven assemblies. The seven lamp stands are seven assemblies.
The first verse of the book of Revelation provides information about the content and genre of the book. The Greek term apokalypsis (ἀποκάλυψις) means an unveiling or disclosure, and reflects a type of literature that became popular in the early second century A.D., but is also found in the Old Testament. The Revelation written by John the apostle (1:4) is much more, however, because it is also a prophetic book given by a Jesus through an angel sent by Him (cf 1:3; 19:10; 22:7, 10, 18-19). The apocalyptic works of the next century are regularly pseudonymous, bearing the name of famous people, but writing by unknown people, whereas John's authorship of the Revelation is attested by several church fathers, including Tertullian, Justin, and Ireneaus).
The book is penned by John but comes from Jesus and is about Him. After the introduction of Jesus and the angel, we see a statement that reflects a similar kind of genre written by Daniel the prophet, and contains a similar statement found in verse one: "things which must happen soon" (Dan 2:28, 29, 45) This is not an indication that the events spoken about in the Revelation would occur within a short time after John is given the revelation from Christ. Rather, the events spoken about will occur in the future and in rapid succession (en tachei, έν τάχει) when they begin to occur.
Also see the Word Study on Revelation and the Note "Who Wrote the Revelation" in Rev 1:1, HVSB.