The Maxim (or Dallas) DS18B20 is a pretty versatile device. For example, you can connect multiple devices to a single data line. You can also establish alarm set points and thus use the DS18B20 to monitor for over temperature and under temperature conditions.
At +/- 0.5 degree C stated accuracy, it also offers measurement accuracy not found in other devices commonly used with an Arduino.
This mult-part user manual will step you through all the basics of using the DS18B20 with your Arduino.
The Basics – Part 1: This section provides a description, basic specifications and offers a tutorial that will show you how to connect your Arduino to your DS18B20.
Getting the DS18B20 Address – Part 2: Each DS18B20 has its own address. While it is possible to use a DS18B20 without knowing that address, knowing how to acquire and use that address is necessary for many types of projects.
This section will show you how to get that address.
Reading a Single DS18B20 – Part 3: In many projects, all you will want to do is get a temperature from a single device. This section shows you how to accomplish that using a couple different methods.
Reading DS18B20 Temperature Alarms – Part 4: Imagine a project where you needed to shutdown your motor before damaging it. With the DS18B20 its just a matter of set an alarm set point within the DS18B20 and monitoring for the alarm.