Word 2013 provides a feature for easily merging a document with multiple versions. It is useful when multiple users work on document that may be combined later. When combiniing the document versions all changes are highlighted and you can easily see what was changed in each version.
To combine multiple document versions use the following.
Open the document that you want to combine with other versions.
Click the Review Tab.
Choose the Combine from Compare drop down list of the "Compare" group.
The Combine Documents window will be opened that has two parts, the original one on the left side and the revised document on the right side.
And you can select the More option to see advanced settings for combining two documents.
Now a new document will be opened where you will see three different windows; the left side has two windows, one for each of the original and revised one and the right side has the combined document.
The combined document uses a red foreground showing where changes exist. When you click on the red text, it will show the changes in a different color.
Now you can choose Accept or Reject to accept or reject the changes within the Review tab.