A database includes multiple operating system threads which are responsible for executing tasks.
There are two types of threads: user kernel threads (UKTs) and special threads. The number of user kernel threads and special threads depends on the hardware configuration, the number of volumes used, and the way the database parameters are set.
Database Administration, Database Parameters
Concepts of the Database System, Threads
Database Studio, Displaying Information About Threads
Database Administration in CCMS, Thread Overview