Was just wondering how long are our breaks in uni? And I heard you start completely new subjects every semester so subjects from the previous semester don't really overlap and stuff? I'm pretty clueless on anything uni related. But back to the main question, how long are holidays in uni? I'm asking because I want to go overseas next year between Jun and August (around there) and was wondering if we have any break during that time (since it's winter here and everything).
Generally, you get most of july on holidays (4 weeks - perhaps longer if you don't have any exams).
Over christmas you get from around end of november (21 november) to about end of february/beginning of March.
However this is dependent on the university - ANU has slightly different holidays, as do uni's such as UNE etc (ie. a couple of weeks difference). Some uni's also don't have a two semesters a year and are opting for 3 semesters, with one over the longer summer break.
As to whether subjects build on each other, that really depends on what you are doing. For example, most of my ancient history units are relatively self-contained, and don't assume factual knowledge from other courses (apart from general skills gained through essay writing/interpreting the past etc). However subjects like Maths, Science and languages can definitely require actual knowledge from previous subjects. Same with law (depending on the subject - one of my subjects is assessing information learnt in a subject last semester in my exam as it is very much the foundation of the course).
edit: if you know which university you would like to attend next year, the semester dates are probably already on their website.