To paraphrase is to rewrite a section of text with the intention of describing a key point within it. This may take more words, a similar number, or fewer words.
So to paraphrase the sentence above ...
Rewriting a section of text using some but not all of the words in the original, to convey the same core meaning, is called paraphrasing.
A paraphrase may not be a summary - in the example above there is no reference to the number of words, which is covered, in the original text.
It isn't a quotation - this would be the exact text repeated.
You must always acknowledge the source of a paraphrase. If you do not, this may be seen as plagiarism.
When there is no equally effective (for your purposes) direct quotation.
This may be because:
If you can use an effective quotation then do.
However, if you are using several references in quick succession, then a mixture of quotations and paraphrases may give a less broken-up, smoother style.
Remember, all quotations and paraphrases must be acknowledged with an in-text citation and a reference in the References section at the end of the piece of work
In his book Blink, The Power of Thinking Without Thinking (2005) Malcolm Gladwell introduces the concept of clear and accurate decisions happening "in the first two seconds" (p. 8). He cites an example of Gianfranco Becchina, an art dealer who tried to sell a sculpture dating back to the sixth century BC to the Getty museum. The statue was submitted to extensive testing all of which suggested it was genuine. However, an increasing number of art historians were saying that it didn't "look right" (p. 5). In the words of Thomas Hoving, former director of the Metropolitan Museum of Art in New York ""It was 'fresh' – 'fresh'," Hoving recalls. And "fresh" was not the right reaction to have to a two thousand year old statue." (p. 5-6) The consensus amongst many experts was an ""intuitive repulsion"". In fact the statue was a forgery made in the early 1980s. The key for Gladwell was that the art experts "In the first two seconds of looking - in a single glance - they were able to understand more about the statue than the team at the Getty was able to understand after fourteen months." (p. 8)
This is a way of using a paraphrase to reduce the length of a quotation while quoting just a particularly effective sentence or important expression or phrase. This is useful if you find it hard to paraphrase a particular phrase or sentence, but have no problem with the rest.