The following terms refer to statutory law: acts, statutes, codes, and bills. Statutory law in California consists of the Constitution plus acts passed by the California Legislature and signed by the Governor. These laws are then organized into Codes (organized by topic), which are published to reflect current law. Similarly, other states' laws are passed by the legislature (sometimes called a General Assembly), signed by the governor and codified into codes having either topical titles (e.g., California's Business & Professions Code or New York's Corrections Code) or a numeric identifier (e.g., Connecticut's Title 33, corporations law). Most states have an annotated code, which can give you additional background, history, relevant cases, and sometimes law review articles (if available) to the law.
Nexis Uni (formerly LexisNexis Academic) is the easiest source to use for current state law "on the books":
Other sources for California statutory law:
If you want the text of law as it was originally enacted and signed by the governor, without any changes that may have amended the law since original enactment, go to the Statutes of California and Amendments to the Code.
For background on the process that led to enactment of a California law, you can try to find legislative history documents related to the drafting and passage of the law. The Law Library's research guide on finding legislative history documentation takes you through that research process step by step, but the most productive and informative documents to look for are usually to be found in legislative documents called the bill versions (to the extent any contain statements of legislative purpose), legislative intent letters, and the Governor's chaptered bill file.
Nexis Uni (formerly LexisNexis Academic) is the easiest source to use for current state case law "on the books"
See the tab on Federal Laws on the Books, and follow the instructions in the box called U.S. Law Sources - Background for Cases. The process is the same for using the Shepard's service to look up materials that have cited to a state court opinion.
Many California cities have their local codes online. Outside of California, locating local county and city laws can be difficult because not all local governments have posted their laws online. Below are some strategies for locating local laws:
Note that, in many jurisdictions, while there are courts called municipal, city or county courts, there generally is no "case law" at the local level. Decisions or rulings based on local laws may be issued by a variety of courts, but state courts at the appellate or high court level are the only courts which can announce decisions that interpret or apply laws in a way that can be called judge-made law.
Statutes - often simply called laws - in states are laws created by a legislative body, often called the Legislature or the General Assembly. Statutes are usually organized and published as a "Code," "Consolidated Laws," or other system of "codified" law. The current codified law publication for any state represents the state's "law on the books" in effect now - for California, this is published privately by two companies, as West's Annotated California Codes and Deering's California Codes, Annotated..
Case law - also called opinions, court rulings, decisions, or just cases - are a form of "judge-made" law in that cases can set forth legal rules and interpretations of other laws. In state courts, these are published in different "reporters" that collect case law from the various states, usually only from the appellate and high (supreme) court levels. For example: