A fixed resistor is the one having a fixed, defined electrical resistance which is not adjustable.  Fixed resistors are the most commonly used resistors and in general one of the most used electronic components. Fixed resistors are available in surface mount packages and axial leaded  as well as more customized packages depending on their application. Axial leaded resistors used to be the most popular one, but now  SMD resistors gain more market share.

The following resistor symbols are often used to depict resistors with a fixed value. The left international IEC resistor symbol is the most used symbol , the left one is the American resistor symbol 

Fixed resistor symbol                                                                                                 Fixed resistor symbol ANSI standardIEC standard

Ideally a perfect resistor would have a constant ohmic resistance under all circumstances. This resistance would be independent of for example frequency, voltage or temperature. In practice no resistor is perfect and all resistors have a certain stray capacitance and inductance, resulting in an impedance value different from the nominal resistance value. The resistor materials have a certain temperature coefficient, resulting in a temperature dependency of the resistor value. The different resistor types and materials determine the dependency of the resistance value on these external factors.