The CD4015 is a Dual 4-bit Shift Register. It has a wide operating voltage upto 18V. The IC is commonly used as I/O expander along with microcontroller to control multiple outputs like LED, LCD display etc..
Dual 4-bit, Serial In – Parallel out Shift register
It can receive (input) data serially and control 4 output pins in parallel. It is often used in projects where relatively a large number of LED’s has to be controlled through the Microcontroller. It can also be used to interface LCD screen since they can acts as the data bit for the LCD displays.