Patmos
Patmos is an island in the Aegean Sea, named once in scripture as the location where John received the visions recorded in the Apocalypse.
John on the Isle
In the opening salutation of Revelation, John identifies himself with his readers and discloses his circumstances: "I John, your⁺ brother and copartner with you⁺ in the tribulation and kingdom and patience [which are] in Jesus, was in the isle that is called Patmos, for the Speech of God and the testimony of Jesus" (Re 1:9). The verse links his presence on the island directly to his witness — he is there on account of the Speech of God and the testimony of Jesus — and it is from Patmos that the visions of the book proceed.