If an idea wasn't yours, you should cite it in-text.  This includes:

• Direct quotations
• Paraphrasing (putting someone else's ideas into your own words)
• Using an idea that someone else gave you in a conversation, email, class, etc.
• Describing an idea that influenced your work
• Expert opinion or lending authority to your own opinion
• Giving any information that isn't common knowledge
• Using any or all of a previously created work of your own design (yes: self-plagiarism is a real thing)

Paraphrasing is taking someone else's idea or statement and putting it into your own words.  It is still considered plagiarism if you paraphrase without an in-text citation.

For example:

Correctly Paraphrased:

Montoya greets, informs his foe of the reason for his anger, and immediately issues a threat (Lear & Reiner, 1987). 

*note that Lear and Reiner are the producer and director of the film The Princess Bride. 

The Princess Bride - Hello my name is Inigo Montoya Face T-shirt [image]. (n.d.). Retrieved from http://www.meta-cortex.com/the-princess-bride-inigo-montoya-t-shirt