What is presenting someone else's work or ideas as your own without crediting the source called?

Plagiarism is the representation of another author's language, thoughts, ideas, or expressions as one's own original work.

Generally, plagiarism is not in itself a crime, but like counterfeiting, fraud can be punished in a court for prejudices caused by copyright infringement, violation of moral rights, or torts. In academia and industry, it is a serious ethical offense. Plagiarism and copyright infringement overlap to a considerable extent, but they are not equivalent concepts, and many types of plagiarism do not constitute copyright infringement, which is defined by copyright law and may be adjudicated by courts.

Not all countries hold the same beliefs about personal ownership of language or ideas. While some, such as India and Poland, consider plagiarism to be a crime liable for imprisonment, in other countries the reiteration of another professional's work can be a sign of respect or flattery.