Content includes all the items that are a part of your course, and D2L allows you to place items in your course in a variety of ways.
After creating a module, notice the options New and Add Existing Activities.
While adding content items is standard, many of your items may be files. D2L files should be thought of as the web pages that you're creating for your course. If, for example, you wanted to have a project introduction page, you would most likely need text, links, images, or videos all in one place. That place (or webpage) is called a File.
Creating a File & Inserting Stuff
D2L has some language that is helpful to know as you get started.
This example, from a module on how to use Microsoft Word, shows a fully-developed file that includes text, images, links, and videos. Notice how the "Create a File" option allows you to better organize content. Once you create a file, it can become one of the items in your module. The D2L text editor is easy to use and requires no knowledge of coding.
To create a file:
In addition to text editing, you may also use the Insert Stuff option for adding content to a File: