the quarter system is comprised of 10 weeks, plus finals week. winter break comes between fall and winter quarters and spring break comes between winter and spring quarters. summer break is from june 17-sep 29. we have two summer sessions available in the summer, 6 weeks each.
the good part about quarter system is that more chances to get good grades, and the classes are split into three quarters, instead of two. so for example, physics, first quarter was kinematics/mechanis, second electricity+magnetism/fluid, third was electromagnetism/optics. the bad part is that midterms come up so fast since the entire quarter is only 10 weeks long. all the UCs are on quarter system, except UC berkeley, its on semester, and graduation was last week for them (i went to my cousins there).
hope that helps.