Giving credit to the original author by citing sources is the only way to use other people's work without plagiarizing. But there are a number of other reasons to cite sources:
- citations are extremely helpful to anyone who wants to find out more about your ideas and where they came from.
- not all sources are good or right -- your own ideas may often be more accurate or interesting than those of your sources. Proper citation will keep you from taking the rap for someone else's bad ideas.
- citing sources shows the amount of research you've done.
- citing sources strengthens your work by lending outside support to your ideas.