Raspberry Pi Pico W is Raspberry Pi's first wireless microcontroller board, designed especially for physical computing. It is the successor of the popular Raspberry Pi Pico board. Similar to the Pico board,  the Pico W board is also built around the Raspberry Foundation in-house ARM chip RP2040.
The main improvement is the addition of Wi-Fi and Bluetooth functionality. Raspberry Pi Pico W incorporates an Infineon CYW43439 wireless chip that supports IEEE 802.11 b/g/n wireless LAN, and Bluetooth 5.2 (not yet implemented in software).
Raspberry Pi Pico W is pin-to-pin compatible with the older Pico board and has a total of 40 Pins out of which 26 are multipurpose GPIOs. These 26 digital input and output pins are labeled as GP0, GP1, and so on up to GP28.
Out of these 30 pins, GP23, GP24, GP25, and GP29 are not exposed on the header, hence we only get a total of 26 GPIO pins. All GPIOs are operating at a 3.3V logic level.  Apart from these pins, Pico w also offers a 3-Pin header for debug interface which is located near the RP2040 Chip.
 
Raspberry Pi Pico W Specifications
 
RP2040 microcontroller chip designed by Raspberry Pi in
Dual-core ARM Cortex M0+ processor, flexible clock running up to 133 MHz
264kB of SRAM, and 2MB of onboard Flash memory
On-board single-band 2.4GHz wireless interfaces (802.11n)
Castellated module allows soldering directly to carrier boards
USB 1.1 Host and Device support
Low-power sleep and dormant modes
Drag & drop programming using mass storage over USB
26 multi-function GPIO pins
2×SPI, 2×I2C, 2×UART, 3×12-bit ADC, 16×controllable PWM channels
Accurate clock and timer on-chip
Temperature sensor
Accelerated floating point libraries on-chip
8×Programmable IO (PIO) state machines for custom peripheral support
 
The main difference between the Pico and Pico W is the inclusion of Infineon’s CYW43439 2.4-GHz Wi-Fi chip, which is responsible for WiFi and Bluetooth. Another major change is with the power section. The new Pico W uses the RT6154A from Richtek as the power regulator instead of the RT6150B in the original Pico design. The debug port also moved near the SoC to make space for the Wi-Fi antenna.
To power the Pico W, you can either use the USB port or VSYS pin.
The simplest way is to use the USB port(5V). This 5V can also be accessed from the VBUS pin for external components.
Another way is to use the VSYS pin (1.8 V-5.5 V) which can be connected to a battery or other similar power source. This input voltage is then converted to a suitable 3.3 V by an onboard voltage regulator.
 
How to program the Pi Pico W?
The new Pico W can be programmed using C/C++ and MicroPython. You can use Thonny IDE for micro python programming. The Pico W board can also be programmed with the Arduino IDE.