When writing, we can use sources in a variety of ways:

Sources can be used to provide context, explain history, and/or outline the current situation.
Sources can be used as primary texts to be analyzed.
Sources can be used to create the conversation of critical views and relevant scholarship surrounding the writer’s question.
Sources can be used to reference the theories, frames, or methods the writer is employing.

You can also:

Use sources to support your claim
Use sources to refute or disprove someone else’s claim
Agree with sources
Disagree with sources
Apply the information in sources to another topic (example: if a particular scholar claims [with evidence] that fans of Doctor Who value the morals/ethics that the main character portrays, then perhaps fans of another television show do the same)

But then comes the next step: actually, literally, writing about these sources.

Summary, Paraphrase, and Direct Quotes

There are three major ways to include information from secondary sources in your paper: paraphrase, summary, and direct quotes.

By the way, you must still cite your source when summarizing, paraphrasing, or using direct quotes.

Consider the following quote (found on the OWL Purdue site):

"Lester, author of Writing Research Papers, writes that “students frequently overuse direct quotation in taking notes, and as a result they overuse quotations in the final [research] paper. Probably only about 10% of your final manuscript should appear as directly quoted matter. Therefore, you should strive to limit the amount of exact transcribing of source materials while taking notes“(47)."

Now we'll look at the differences between paraphrase, summary, and direct quotes.

Paraphrase

When paraphrasing a passage from a text, you should:

Restate all of the information in a passage:
- in your own words
- using your own sentence structure
- with your audience in mind.
Cite your source

Don’t just change one or two words in each sentence (that's close enough to a direct quote to be considered plagiarism), use your own style!

Paraphrasing is useful when:

the original passage contains language inappropriate for your audience
the original passage might be difficult for your audience to understand
quoting the original passage would break the flow of your writing
all of the information in the original passage in important for your paper

This is a paraphrase of the original passage from above:

In research papers students often quote excessively, failing to keep quoted material down to a desirable level, which is about 10% of the final paper. Since the problem usually originates during note taking, it is essential to minimize the material recorded verbatim (Lester 46-47).

Notice that it has a similar word count to the original, and has all of the major points and statistics.

Summary

In a summary you should:

State only the main ideas of a text, usually condensing the original text to only a few lines.
Describe the author’s key claims
Select examples to illustrate the author’s argument
Present the gist of the author’s information
Cite your source

In other words, it's the tl,dr (too long, didn't read).

Summary is useful when:

the original text is too long to quote in a paper
the original text has a lot of information that is not necessary for your paper

This is a summary of the original passage from above:

Students should take just a few notes in direct quotation from sources to help minimize the amount of quoted material in a research paper (Lester 46-47).

Notice how it's far shorter than the original, but keeps Lester's main idea.

Direct Quotes:

When you quote an author directly you should:

Use the exact words the original author used.
You can skip words by enclosing an ellipses in square brackets like this [...].
Enclose the entire quote in quotation marks
Cite your source

When should you use direct quotes?

Short answer: not often.

Long answer: Direct quotes are useful when:

the author’s exact words are important
there is no better way to say (paraphrase/summarize) the quote

It is usually better to summarize or paraphrase. Using a direct quote is like bringing out the big guns, taking the gloves off, and all sorts of other clichés. Those quotation marks are a sign to the reader that the words in quotation marks should be paid close attention to. If the direct quote isn't particularly important, it makes the rest of your quotes seem less important, too.

But more than that, quotation marks are someone else's work, not yours. Using direct quotes shows your reader that you can find and copy words exactly. It does not prove that you understand the quote you used, and a direct quote on its own does not explain why that quote is necessary. Summary and paraphrase can do both of those things, and still count as citations. This can lead to better papers, and from there, better grades.