Most teams that write code adopt a common style to make reading each other’s code easier. The choices in that common style usually have good reasons but are sometimes an arbitrary choice between several good options.
The CS135 team (faculty, staff, students) along with the teams in several other UW courses use this style guide. Failure to be a team player with respect to the style guide will have adverse consequences on your marks.
As a comparison, you may want to look at Google’s style guide for C++.