The consequences associated with plagiarism depend largely on the context, but they can include scholastic disciplinary action or potential civil or criminal charges. This is normally determined based on the potential for monetary gain resulting from the plagiarized work.
In most cases, plagiarism occurs as part of a scholastic assignment. In an effort to save time and improve their final grade, students often turn in work which is either partially or completely copied from another work. The risk of this has increased with the ubiquitous presence of the Internet, allowing access to new information and material. Most educational organizations have a zero tolerance policy for these events, and consequences can range from academic probation to expulsion. From a legal perspective, plagiarism is essentially copyright infringement. If a work has been documented as copyrighted by the original author or creator, then they have legal grounds to pursue civil litigation or even criminal charges against the perpetrator. Whether long term or short term, the aftereffects of plagiarizing work can be detrimental. This may be as minor as damaging a student's reputation and their instructors' trust in them, or it may end with a criminal charge. In any case, it's often worth it to simply do the research and create something original rather than taking the risk.