The purpose of having in-text citations is to ethically give credit to other's ideas within your paper. This information is like a quick link to your Works Cited list where anyone can get further details about your source and find it themselves. The provided information is brief and should not distract the reader from the "flow of ideas" (MLA 54).
Basic information to include:
The full citation, on the works cited page, will look like this:
Smith, Joe. "In-text Citations." Academic Ethics, Lone Star Press, 2016, p. 123.