The most common perception about plagiarism is copying another person's work verbatim without doing any research and naming it as one's own creation. Penn State University terms this as wholesale copying. However, incorporating large chunks of text from a source into your work or inadequate paraphrasing of the information from a source is also considered plagiarism.
Pressure from parents to excel and anxiety of competition with peers trigger fear of failure in many students. In their zeal to excel, some students incorporate ideas of others in their assignments hoping they won't be caught or believing that the minor changes that they made in their assignment make it non-plagiarized.
There are certain techniques that can prevent plagiarism. For example, giving credit to the author while using his ideas or using sentences or phrases used from the source as quotations, prevents plagiarism. Another way of preventing plagiarism when using someone's idea is to use a citation--in text or parenthetical--to identify the language or idea is not yours.
Despite being aware of the techniques, many students do not employ them because they do not want to put in the effort of turning in an original piece of work. They either think they won't be caught or are unaware or not bothered about the consequences of plagiarism. Besides this, some individuals suffer from what Webster University terms as the "writing anxiety." Even if such individuals want and do research, they cannot express their findings in words.
Procrastination may be one of the reasons why one may be forced to copy another person's work. Sometimes students fail to plan their time properly. Heavy academic pressure has been cited by Penn State University as one of the reasons why students plagiarize others' work.