-Currently only the slash `/` is recognized as the "magic signature",
-but it is envisioned that we will support more types of magic in later
-versions of git.
+Two consecutive asterisks ("`**`") in patterns matched against
+full pathname may have special meaning:
+
+ - A leading "`**`" followed by a slash means match in all
+ directories. For example, "`**/foo`" matches file or directory
+ "`foo`" anywhere, the same as pattern "`foo`". "`**/foo/bar`"
+ matches file or directory "`bar`" anywhere that is directly
+ under directory "`foo`".
+
+ - A trailing "`/**`" matches everything inside. For example,
+ "`abc/**`" matches all files inside directory "abc", relative
+ to the location of the `.gitignore` file, with infinite depth.
+
+ - A slash followed by two consecutive asterisks then a slash
+ matches zero or more directories. For example, "`a/**/b`"
+ matches "`a/b`", "`a/x/b`", "`a/x/y/b`" and so on.
+
+ - Other consecutive asterisks are considered invalid.