What is the difference between a Professor, Associate Professor and Assistant Professor?

What's the difference between a professor and a lecturer?

• every time I look at the faculty list for a university, I always see the teaching staff list split up between professors and lecturers. What's the difference between the two. Also, what's the difference between a regular professor, an assistant professor, and an associate professor?

• Answer:

  In the US, professor is a tenure-track position, lecturer is not. While professors who get tenure (almost) can't be fired, lecturers are shorter-term positions and not guaranteed (although usually longer term than adjuncts, who might be hired just for a single semester at a time). Professors start out at the assistant level, rise to associate when they get tenure (5-10 years later), and become a full professor a few years after that.