What are the different ACPI power states, and how do they differ?
ACPI defines several power states, often referred to as "system sleeping states" (S-states) and "device sleeping states" (D-states). Here are the most common ACPI power states and how they differ:

S0 (Working or Active State): This state represents the normal working state of the system. The CPU and other devices are fully powered, and the system is operational. In this state, the system is fully active and responsive to user input.

S1 (Standby or Sleep State): In this state, the CPU is stopped or placed into a low-power mode. However, the system RAM remains powered to retain data, and the system can quickly resume to full operation upon user interaction. S1 is an intermediate power-saving state where the system is still relatively active.

S2 (Sleep State): Similar to S1, the CPU is stopped or put into a low-power mode, and the system RAM remains powered to retain data. However, S2 offers greater power savings by allowing additional components to be powered down. It takes longer to resume from S2 compared to S1.

S3 (Standby or Suspend to RAM): In this state, also known as "Suspend to RAM," the system is in a low-power state where most components, including the CPU, are powered off, except for the RAM, which retains data. The system appears to be off but can quickly resume to full operation since the RAM contents are preserved.

S4 (Hibernate): Also known as "Suspend to Disk," in this state, the contents of RAM are written to disk, allowing the system to completely power off. Upon resuming from S4, the system restores its previous state from the disk image. S4 has a longer resume time compared to S3 but offers greater power savings.

S5 (Soft Off or Shutdown State): This is the lowest power state where the system is completely powered off, and no power is supplied to any components except for wake-up devices such as a power button or network interface for Wake-on-LAN functionality. The system must be restarted to resume operation from S5.
Below is an instruction that describes a task. Write a response that appropriately completes the request. ### Instruction: What are the different ACPI power states, and how do they differ? ### Response: ACPI defines several power states, often referred to as "system sleeping states" (S-states) and "device sleeping states" (D-states). Here are the most common ACPI power states and how they differ:

S0 (Working or Active State): This state represents the normal working state of the system. The CPU and other devices are fully powered, and the system is operational. In this state, the system is fully active and responsive to user input.

S1 (Standby or Sleep State): In this state, the CPU is stopped or placed into a low-power mode. However, the system RAM remains powered to retain data, and the system can quickly resume to full operation upon user interaction. S1 is an intermediate power-saving state where the system is still relatively active.

S2 (Sleep State): Similar to S1, the CPU is stopped or put into a low-power mode, and the system RAM remains powered to retain data. However, S2 offers greater power savings by allowing additional components to be powered down. It takes longer to resume from S2 compared to S1.

S3 (Standby or Suspend to RAM): In this state, also known as "Suspend to RAM," the system is in a low-power state where most components, including the CPU, are powered off, except for the RAM, which retains data. The system appears to be off but can quickly resume to full operation since the RAM contents are preserved.

S4 (Hibernate): Also known as "Suspend to Disk," in this state, the contents of RAM are written to disk, allowing the system to completely power off. Upon resuming from S4, the system restores its previous state from the disk image. S4 has a longer resume time compared to S3 but offers greater power savings.

S5 (Soft Off or Shutdown State): This is the lowest power state where the system is completely powered off, and no power is supplied to any components except for wake-up devices such as a power button or network interface for Wake-on-LAN functionality. The system must be restarted to resume operation from S5. 