Using images, especially photographs and cartoons that you did not create, without attribution is plagiarism. Leaving out the attribution implies the work, idea, and image are your creation. It is better to tell everyone where you got your images (including cartoons, photographs, and other artwork) that you did not personally create.
Everything is a Remix. An interesting site with videos that addresses the intersection of creativity and copying.
Data is often an important part of writing a research paper. When you take the time to find quality data to support your argument, take a minute longer to provide a correct citation. That tells the professor you have done your homework and shows where your own data collection efforts stopped. Cite the book, article or database where you retrieved that excellent data. It shows you know where your work stopped and tells your audience where to go for more in-depth work on the topic.
Using computer code without citing it correctly may be considered plagiarizing. In some classes, it is also considered cheating especially when the assignment is to develop your own code. However, there are common codes used routinely within more complicated programs. Details about options and citing mechanism can be found on a related Research Guide through the link below.