What is the Difference Between a Fuse and a Circuit Breaker?
Fuses and circuit breakers serve a very similar function - both break electrical circuits in the event of a current surge or short circuit. However, there is a crucial difference. Circuit breakers are switches, and like all switches, they can be reset once they have been flipped. Most fuses, though, can only be used a single time. Once they have blown, they must be replaced. They are, by definition, a weak link - entirely by design.
Fuses are inexpensive and can be replaced (pulled) quickly and easily for minimum downtime. It is important to ensure that you fit a fully compatible model with the correct current rating for your device. This figure indicates the level of current the fuse will accept before blowing.
There are other relevant metrics. The speed rating indicates how quickly the fuse will blow in response to excess current; a more sensitive fuse is a safer option. Voltage drop is the voltage lost through cables due to impedance - essentially when the voltage at the end of a run of cable is lower than at the beginning. If too much is lost, some low equipment may not function correctly. It is also sensible to check the amount of energy released by the fuse when blowing. Too much could cause damage to the device and even be hazardous.
How Does a Fuse Work?
Fuses are very simple components. Inside each is a thin metal strip or wire called a resistor that forms a link in an electrical circuit. A number of different metals are used to make resistors. Tinned copper wire is a popular choice. This is copper which has been coated in a thin layer of tin to protect against corrosion.
This resistor will melt in response to the heat generated by the excess current, breaking the circuit and stopping the flow of potentially hazardous voltage. Fuses do not produce sparks, gas or electrical discharge. 
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