Putting the information and ideas from another’s work into your own works is called Paraphrasing. Paraphrasing rather than using direct quotations allows you to demonstrate that you really understand the concepts being discussed. It also allows you to integrate the information you are using more smoothly into the rest of the material.
Simply changing a few words, or rearranging the order the information appears in is not sufficient. Even though you will be providing a reference for the material used, without genuinely putting the information into your own words, you will be plagiarising the original work.
Tips for successful paraphrasing
1. Carefully read the relevant resources, and note any key points that you wish to use separately
2. Note each source used for later reference
3. Without looking at the original material, write out the idea in your own words
4. Use quotation marks if you have included any direct quotes.
5. Check that you have accurately conveyed the ideas in the material used, and not put your own interpretation on it.
6. Check that what you have written does not use the same phrasing as the original source. Remember that making a few minor changes to the material is not sufficient.
7. Include both the in-text citation, and a complete reference
Examples of acceptable and unacceptable paraphrasing
The following is an extract from the 30th IEEE Real-Time Systems Symposium :
“A key feature of control systems is robustness, the property that small perturbations in the system inputs cause only small changes in its outputs. Robustness is key to designing systems that work under uncertain or imprecise environments. While continuous control design algorithms can explicitly incorporate robustness as a design goal, it is not clear if robustness is maintained at the software implementation level of the controller: two “close” inputs can execute very different code paths which may potentially produce vastly different outputs”
The following is an acceptable paraphrase of this extract:
A robust control system is one where system outputs are not significantly affected by minor changes in system inputs.
In situations where operating conditions are not precisely known, the ability of the system to achieve robust performance becomes increasingly important. However, even systems that are designed to achieve robustness may not achieve it under all conditions. Where different code paths are triggered, significantly different outputs may result from similar inputs. 
Note that it is not necessary to include all of the information from a paragraph or article in your work; only include what is pertinent to your argument. Often this would just be one key fact or idea, rather than most of the paragraph..
The next version is an unacceptable paraphrase of the same extract:
Robustness is a key feature of control systems. Robustness is the property that small perturbations in the system inputs cause only small changes in its outputs. Robustness is important when designing systems to work under uncertain or imprecise conditions. However it is not clear if robustness is maintained at the software implementation level of the controller, even if the continuous control design algorithms incorporate robustness explicitly as a design goal: even ‘similar’ inputs can give significantly different code paths producing very different outputs
This version is really just a re-organised version of the original, with a few words and phrases changed throughout. It doesn’t demonstrate an understanding of the concepts involved, or that the application of these concepts to the topic under discussion has been understood.
The second version has also not acknowledged the source of the work.
If you use the same wording as the source document, this is called a quotation. These must be enclosed within quotation marks in your work, and the relevant page number/s given.
‘XML is a new language developed from SGML and is expected to eventually replace HTML as the “language” of Web Browsers' [1, p7]
Generally, it is preferable to try to put the information into your own words, and to reserve direct quotations either for including relevant facts and figures (that are not common knowledge) or for particularly memorable wording. Select quotations that give weight to your arguments, not ones that only repeat information that you have already given.
In texts citations should be numbered sequentially, using square brackets, in the order that they appear in the text. Each subsequent use of the same reference would continue to use that same number.
There is generally no need to mention authors or dates in in-text citations, simply say, for example: “In  it is shown…” or “Recent studies [4,5,8] have indicated..”
The citation should appear directly following the reference, rather than at the end of the sentence or section.
 J.H. Pence, How to do everything with HTML. Berkeley: McGraw Hill, 2001.
 R. Majumdar and I. Saha. "Symbolic robustness analysis," in 30th IEEE Real-Time Systems Symposium, RTSS 2009, Washington, DC, USA, 1-4 December 2009 [Online]. Available: https://www.researchgate.net/publication/221298612_Symbolic_Robustness_Analysis [Accessed Jul. 17, 2009].