Clock Generation and Distribution
Clocks are needed for various functions of a computing device containing processor, memory, and input and output peripherals. Each of these components requires different clock speeds specified by different standards. The core operating frequency is in the gigaherts range, memory clocks speed is in hundreds of megahertz range, and I/O transceivers interface can be slow as 10s of KHz to fast in the giga herts range.
All these clock speeds comes from a signal source of clocks that can be scale up or down to meet the needs of each components in a computing device. a clock generator takes a high quality clock source such as a crystal oscillator and scales up using a phase locked loop and then divided down to various clock speeds needed in the system. Then various clock source are distributed to the target hardware blocks such as core, transceivers, and peripherals devices.
Play around with TI Clock generator to understand how each frequency is generated and distributed.
An example of Clock Generator IC
An example of a Clock Tree: Page 3 https://www.mouser.com/pdfdocs/clock-tree-101-timing-basics.pdf