AVR lock bits and fuses are one of the topics that may cause some confusion. If you missed something or set one bit wrong, it may lead to failure – bricking the whole AVR chip. So it is important to understand once and do things right. Even though datasheets give enough information about AVR fuses, many times, we feel somewhat unsure before executing the write command. Let us go through the main features of AVR fuses and lock bits so next time we would feel safe and get the expected results.