Internship is an on-the-job training opportunity provided to students while they are pursuing and graduate or post graduate degree. In other words it offers students a hands-on opportunity to work in their desired field. They learn how their course of study applies to the real world and build valuable experience that makes them stronger candidates for jobs after graduation.
Yes, you should include starting and ending dates for each employer listed in the work history section. It’s best to show both months and years. If you decide to show only years, a discerning hiring manager may wonder why you aren’t providing more detail.