In addition to standardizing the core elements required for a citation, MLA 8th also introduces the concept of containers. MLA states:
"The concept of containers is crucial to MLA style. When the source being documented forms part of a larger whole, the larger whole can be thought of as a container that holds the source. For example, a short story may be contained in an anthology. The short story is the source, and the anthology is the container."
When citing, the title of the container is generally italicized and is followed by a comma. For example, for articles in journals, the journal is the container that holds the article.
Baron, Naomi S. "Redefining Reading: The Impact of Digital Communications Media." PMLA, vol. 128, no. 1, Jan. 2013, pp. 193-200.
(MLA Handbook, 8th ed., p. 30)
Sometimes the source that you are citing has two containers. For example, for articles found in a database, the first container is the name of the journal. The second container is the database where you found the article. Please see the example below.
Academic Search Complete
“Between Image and Word, Color, and Time: Jacob Lawrence’s The Migration Series.” African American Review, vol. 40, no. 3, 2006, pp. 571-86. Academic Search Complete, search.ebscohost.com/login.aspx?direct=true&db=f5h&AN=24093790&site=ehost-live.