We are aware of the need for a burglar alarm and we know the many uses they can provide us with. However, it is difficult to choose the right one without actually knowing how they work. This article goes through the basic of burglar alarms to the most sophisticated systems in a detailed way that is both comprehensive and extremely helpful. The most simple and basic burglar alarm is an electric circuit which is built into an entry way, this seems simple enough; if the circuit gets broken burglar alarm goes off. Another burglar alarm is a motion detector, this detects and intruder that is already in the house and is walking around, this could come in handy. The article takes a step by step approach in explaining what burglar alarms do and why/how they do it, which can be very useful in deciding which burglar alarm is right for you.