Resistors

German: Widerstand

Symbol: R (shortened for Resistance)
Unit for resistance is Ohms, represented by a capital omega: Ω (Example: 1 ohm = 1 Ω). For convenience the capital omega is replaced: 22 Ω is often written as 22 R. Decimal marks like 2.2 Ω are replaced by the unit: 2R2.

Accordingly values with a prefix like 47 kΩ (47 000 Ω) are shortened to 47k. 1 MΩ is written 1M. Decimal marks are replaced like before:
4.7 kΩ is written 4k7
2.2 MΩ is written 2M2

Resistor Color Codes

http://www.elektronik-kompendium.de/sites/bau/1109051.htm (German)
http://www.bader-frankfurt.de/widerstandscode.htm (German)
http://www.csgnetwork.com/resistcolcalc.html (English)