Basketball basic rules are not overly complicated. Sure, every governing body will have their own specific regulations concerning how things are done, and you should be somewhat familiar with the more important ones. But the basic rules, whether you are looking at rules from the NBA, the NCAA, or high school basketball rules, will be more or less the same.
There are three very broad categories of basketball rules that every player and coach should have a decent understanding of, if you want to play basketball and do well. Realize the league you play in is likely to have their own specific version of these rules, but if you compare basketball rulebooks for one league to another, you will find several areas of basketball basic rules pretty much in common.
Basketball Rules Concerning Violations - what moves can your players do with the ball, and what moves aren't legal? i.e., what will your players do with the ball that will cause your team to lose possession of it?
Basketball Rules Concerning Fouls - what type of contact between offensive and defensive players is allowed, and how much of it is not allowed?
A general explanation of the rules of basketball will be all you need under most circumstances - click on the links above for a breakdown in general terms of each type of regulation. Knowing this will get you through the majority of your coaching career, especially true if you coach youth basketball.
The only time when you would really need to understand the rules in more specific terms than the basketball basic rules above would likely be at game time. As mentioned already, every league will have its own set of specific rules, some more detailed and complex than others. Choose the set of rules that applies to your own situation.
The high school basketball rules followed by most schools in the US is from the National Federation of State High School Associations (NFHS). You can't download a free copy of the high school basketball rules like you can from the pros and college leagues, but the NFHS publishes rule books and guides, and a couple are carried by Amazon.
Two NFHS books you may want to buy:
The NFHS 2009-10 High School Basketball Rules by Topic, which not only lists the rules but also explains the rules in everyday language, provides examples and case plays, rationales for why the rule exists, and links rules to related basketball fundamentals. It also includes images of referee hand signals for each rule.
The 2009-10 NFHS High School Basketball Rules Simplified & Illustrated. This book supplements the NFHS basketball rules book, and is focused more on helping officials understand the rules, using plenty of diagrams and illustrations. A good book to have for officials, especially for young or beginning officials or if you are part of a youth league or rec league that uses volunteer referees who may not be familiar with high school basketball rules.
If it's the pros you're interested in, take a look at the NBA rules or the WNBA rules , or if you are interested in international rules, you can check out FIBA rules .
There are also college rules (NCAA ) you should review if you coach at that level or are a die-hard fan.
In general, understanding basketball basic rules is important for every coach and player, but I wouldn't go so far as to say that every coach needs to be able to recite verbatim every single rule in the rulebook for their league. The specific rules are important at game time - always have a copy of the official rules on the scorer's table for reference if a debate ensues - but most of our coaching career takes place during team practices. So for most of our coaching careers, I would suggest a general knowledge of the rules will suffice.