diff --git a/data/glossaries/external.yml b/data/glossaries/external.yml
index eb494a7c241a..ab095361f6b2 100644
--- a/data/glossaries/external.yml
+++ b/data/glossaries/external.yml
@@ -60,9 +60,9 @@
 - term: branch
   description: >-
     A branch is a parallel version of a repository. It is contained within the
-    repository, but does not affect the primary or master branch allowing you to
+    repository, but does not affect the primary or main branch allowing you to
     work freely without disrupting the "live" version. When you've made the
-    changes you want to make, you can merge your branch back into the master
+    changes you want to make, you can merge your branch back into the main
     branch to publish your changes.
 - term: branch restriction
   description: >-
@@ -141,8 +141,9 @@
     Short, descriptive text that accompanys a commit and communicates the change
     the commit is introducing.
 - term: compare branch
-  description: The branch you use to create a pull request. 
-    This branch is compared to the base branch you choose for the pull request, and the changes are identified. 
+  description: >-
+    The branch you use to create a pull request.
+    This branch is compared to the base branch you choose for the pull request, and the changes are identified.
     When the pull request is merged, the base branch is updated with the changes from the compare branch.
     Also known as the "head branch" of the pull request.
 - term: continuous integration
@@ -395,12 +396,18 @@
     Markdown and uses a particular form of Markdown called GitHub Flavored Markdown. See [GitHub Flavored Markdown Spec](https://github.github.com/gfm/) or [Getting started with writing and formatting on GitHub](/articles/getting-started-with-writing-and-formatting-on-github).
 - term: Markup
   description: A system for annotating and formatting a document.
-- term: master
+- term: main
   description: >-
     The default development branch. Whenever you create a Git repository, a
-    branch named "master" is created, and becomes the active branch. In most
+    branch named "main" is created, and becomes the active branch. In most
     cases, this contains the local development, though that is purely by
     convention and is not required.
+- term: master
+  description: >-
+    The default branch in many Git repositories. By default, when you create 
+    a new Git repository on the command line a branch called `master` is created. 
+    Many tools now use an alternative name for the default branch. For example, 
+    when you create a new repository on GitHub the default branch is called `main`.
 - term: Members graph
   description: A repository graph that shows all the forks of a repository.
 - term: mention