All major processor manufacturers have implemented a "DTS" (Digital Thermal Sensor) in their products. The DTS provides more accurate and higher resolution temperature readings than conventional onboard thermal sensors. (How does it work?).
This feature is supported by all recent x86 processors. Processors by Intel, AMD and VIA are supported. A complete list of supported processors is available.

Core Temp is easy to use, while also enabling a high level of customization and expandability.
Core Temp provides a platform for plug-ins, which allows developers to add new features and extend its functionality. You can find our plug-ins and add-ons here.
If you are a developer and you are interested in creating your own addition, please see the developer's page.