The Raspberry Pi 3 is the third generation Raspberry Pi. It replaced the Raspberry Pi 2 Model B in February 2016. Raspberry Pi 3 is the first board to have a 64-bit quad-core processor of the Raspberry Pi family. The 64-bit quad-core 1,2GHz ARM Cortex A53 chip allows the board to almost double the performance of the Raspberry Pi 2.
Compared to its former, Raspberry Pi 3 has:
Like the Pi 2, it also has:
The Raspberry Pi 3 has an identical form factor to the previous Pi 2 (and Pi 1 Model B+) and has complete compatibility with Raspberry Pi 1 and 2. There is a 99% chance that your accessories those work with Pi 2 and Model B+ will work with Raspbbery Pi 3, too. Raspberry Pi 3 Model B is recommended for use in schools, or for any general use.
Official Raspberry Pi 3 Page: https://www.raspberrypi.org/products/raspberry-pi-3-model-b/