The DS18B20 Temperature Sensor provides 9-bit to 12-bit Celsius temperature measurements. DS18B20 also has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 also communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor.
In addition to this the DS18B20 can also derive power directly from the data line (“parasite power”). Which eliminating the need for an external power supply. Each DS18B20 also has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area. Applications that can also benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment. It also includes machinery, and process monitoring and control systems.

Features & Specifications of DS18B20 Temperature Sensor:

1. Unique 1-Wire® interface requires only one port pin for communication
2. Each device also has a unique 64-bit serial code stored in an onboard ROM
3. Multidrop capability simplifies distributed temperature sensing applications
4. Requires no external components
5. It can also be powered from the data line. Power supply range is 3.0V to 5.5V
6. Measures temperatures from –55°C to +125°C (–67°F to +257°F)
7. ±0.5°C accuracy from –10°C to +85°C
8. Thermometer resolution is user-selectable from 9 to 12 bits
9. Converts temperature to 12-bit digital word in 750ms (max.)
10. User-definable nonvolatile (NV) alarm settings
11. Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition)
12. Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system

Applications:

1. Thermostatic Controls
2. Industrial Systems
3. Consumer Products
4. Thermometers
5. Thermally Sensitive Systems

Please follow the link to configure ds18b20 with raspberry pi

  https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing/hardware

Datasheet Of DS18B20:

http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf

Package Includes In DS18B20 :

• 1x  DS18B20 Temperature Sensor