— Command: emacs-version &optional here

This function returns a string describing the version of Emacs that is running. It is useful to include this string in bug reports.

          (emacs-version)
            ⇒ "GNU Emacs 26.1 (build 1, x86_64-unknown-linux-gnu,
                       GTK+ Version 3.16) of 2017-06-01"

If here is non-nil, it inserts the text in the buffer before point, and returns nil. When this function is called interactively, it prints the same information in the echo area, but giving a prefix argument makes here non-nil.

— Variable: emacs-build-time

The value of this variable indicates the time at which Emacs was built. It is a list of four integers, like the value of current-time (see Time of Day), or is nil if the information is not available.

          emacs-build-time
               ⇒ (20614 63694 515336 438000)

— Variable: emacs-version

The value of this variable is the version of Emacs being run. It is a string such as "26.1". A value with three numeric components, such as "26.0.91", indicates an unreleased test version. (Prior to Emacs 26.1, the string includes an extra final component with the integer that is now stored in emacs-build-number; e.g., "25.1.1".)

— Variable: emacs-major-version

The major version number of Emacs, as an integer. For Emacs version 23.1, the value is 23.

— Variable: emacs-minor-version

The minor version number of Emacs, as an integer. For Emacs version 23.1, the value is 1.

— Variable: emacs-build-number

An integer that increments each time Emacs is built in the same directory (without cleaning). This is only of relevance when developing Emacs.