This is the official manual for the latest Org-mode release.
The most common archiving action is to move a project tree to another file, the archive file.
The default archive location is a file in the same directory as the
current file, with the name derived by appending _archive to the
current file name. You can also choose what heading to file archived
items under, with the possibility to add them to a datetree in a file.
For information and examples on how to specify the file and the heading,
see the documentation string of the variable
There is also an in-buffer option for setting this variable, for example1:
If you would like to have a special ARCHIVE location for a single entry
or a (sub)tree, give the entry an
:ARCHIVE: property with the
location as the value (see Properties and Columns).
When a subtree is moved, it receives a number of special properties that
record context information like the file from where the entry came, its
outline path the archiving time etc. Configure the variable
org-archive-save-context-info to adjust the amount of information
 For backward compatibility, the following also works: If there are several such lines in a file, each specifies the archive location for the text below it. The first such line also applies to any text before its definition. However, using this method is strongly deprecated as it is incompatible with the outline structure of the document. The correct method for setting multiple archive locations in a buffer is using properties.