How are verses referenced? How are Bible verses referenced? For example what is the meaning of: Revelation 21:5 (NIV)? 

Are there any other methods to reference a verse?

(I am not a Christian and this should be treated like a novice question.)
The Bible is made up of many different "books", or documents, compiled into a single volume. The traditional Protestant Bible has 66 books.  The Catholic Bible uses 73.  Some other Christian groups also use a few other religious texts, that are usually referenced in the same way.

Each book is divided into chapters (apart from the very short ones, where there is only one chapter) and each chapter is divided into verses.

So Revelation 21:5 (NIV) refers to the book of Revelation, the 21st chapter, the 5th verse, in the NIV (New International Version) translation.

You will most commonly (at least in the U.S.) see verses referenced as:


[Book] [chapter]:[verse] for a single verse
[Book] [chapter]:[verse]-[verse] for multiple verses
[Book] [chapter] for an entire chapter
[Book] [chapter]:[verse]-[chapter]:[verse] for a selection spanning multiple chapters


A small number of books in the Bible have only a single chapter, so then the convention is:


[Book] [verse] for a single verse
[Book] [verse]-[verse] for multiple verses


Often, the name or abbreviation of the translation used will follow, often in parenthesis. This is most customary when quoting the verse that is referenced.

A few other less commonly used notations are:


[Book] [chapter]:[verse],[verse] to reference multiple, non-consecutive verses
[Book] [chapter]:[verse][a,b,c..] to reference the first (a), second (b), etc, sentence of the verse. This addition can be imprecise, as the original greek and hebrew lack punction, so sentence breaks must be inferred by translators, with varying results.
[Book] [chapter]:[verse]ff to indicate "this verse, and following"


Also note that you will occasionally see, in place of a colon (:), a period (.) or the lowercase letter v.  As in:


Revelation 21.5
Revelation 21v5