The AVR is a modified Harvard architecture 8-bit RISC single-chip microcontroller, which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other microcontrollers at the time. AVR Studio is used by embedded programmers for programming and debugging for many of the Atmel microprocessors such as the Atmega8. The Arduino environment is based on Atmel Atmega microcontrollers.
Lots of electronic projects can be made easily using the ATMEL AVR microcontrollers among them clocks, very simple video games, robots, servo controllers, and many more. The 8051 based controllers is one of the most widely used microcontrollers and are very cost effective as well..