There are a variety of different ways to find information in sophisticated commercial online systems such as Westlaw and Lexis Advance.
Arizona Statutes Example
You wish to find the Arizona statute about executing pregnant prisoners.
For legal research, indexes are especially useful because legal concepts are often expressed using different terms. This can make it difficult to locate relevant documents with a keyword search. (And even if you locate some relevant documents you are unlikely to locate ALL relevant documents which is a frequent goal of legal research.)
Examples of Different Ways to Express Legal Concepts
death penalty, capital punishment, execution
murder, homicide, unlawful killing
restraining order, order of protection, injunction
Using a Arizona Revised Statutes Subject Index Example
You have a client who is on death row and is pregnant. You think it is probably illegal in Arizona to execute people while they are pregnant so you turn to the Arizona Revised Statutes on Westlaw.
You know that the concept of the state executing someone as punishment for a crime can be expressed in multiple ways: death penalty, capital punishment, and execution.
A table of contents usually is a list of the parts of a source organized in the order in which the parts appear. The depth of detail in tables of contents depends on the length of the source.
Another Example - A.R.S. § 13-4025
The Arizona Revised Statutes has an table of contents. On Westlaw Edge, you would go to the Arizona Statutes and Court Rules database and look at the table of contents. To find the statutory sections about executing prisoners you would go to the Title 13 - Criminal Code and click through the different chapters until you find something relevant.
You always want to see where your section fits in the table of contents so you will not miss any related sections.