An in-text citation (aka. parenthetical reference) is used when you use someone else's words or ideas within your work. This helps your instructor differentiate between your writing, and the work of others. Doing this helps you avoid plagiarism (stealing someone else's work or ideas). It also shows your instructor that you can integrate the work of others within your own (to support your ideas). Using MLA style, it looks like this:
As Hulme et al. state, students who are more curious "actively seek opportunities for new information and experiences" (56).
Or
Students who are more curious are constantly looking for a variety of experiences related to their academic pursuits (Hulme et al. 56).
Or
Students in the study who were more curious "actively seek opportunities for new information and experiences" (Hulme et al. 56). It's easy to see what behaviors drive one to be curious, but a more interesting question is how to make people more curious. If curiosity is a strong driver of educational interest, how can we inspire this in students?
As you can see, you can create in-text citations in many different ways -- what is important is that you clearly show which words/ideas are YOURS and which words/ideas come from your SOURCES.
(Why does it say "et al."? This is what you do when you have three or more authors. For more information, see the "Citing a work by multiple authors" section on the MLA In-Text Citations: The Basics page by the Purdue Online Writing Lab.)
When your instructor sees your in-text citation, they understand you are using someone else's words or ideas, and if they have questions, they can follow-up on the source by looking to the end of your paper where your References page is located. The information in the in-text citation matches the information in the citation on your References page, which for the example above would look like this:
Hulme, Eileen, Daniel T. Green, and Kimberly S. Ladd. "Fostering Student Engagement
By Cultivating Curiosity."New Directions For Student Services, vol. 2013, no. 143,
2013, pp. 53-64. Academic Search Premier, 0-search.ebscohost.com.library.4cd.edu/
login.aspx?direct=true&db=aph&AN=90469360&site=ehost-live. Accessed 1 July 2016.