The most common IC (integrated circuit) chip depends on the context (consumer electronics, computers, industrial, etc.), but generally speaking, the following three are the most widely used types:

 1. Microcontroller Unit (MCU)

Most common overall in embedded systems.

Combines CPU, memory (RAM/ROM), and peripherals (like timers, I/O) on one chip.
Used in: home appliances, toys, automotive systems, medical devices, and IoT devices.

Example: ARM Cortex-M, Atmel AVR (used in Arduino), ESP32

 2. Operational Amplifier (Op-Amp) IC

Widely used in analog signal processing and amplification.

Found in: audio devices, sensors, signal conditioners, medical equipment.

Example: LM741, TL081, LM324

3. Logic Gate ICs
Handle simple binary operations (AND, OR, NOT, etc.).
Used in all types of digital circuits for control and logic.
Example: 74xx series (e.g., 7400 NAND gate)

In Consumer Electronics:
The most common high-complexity IC is the System on Chip (SoC):
Found in smartphones, tablets, and smart TVs.
Combines CPU, GPU, RAM, modem, etc., in one package.