Make some beautiful colors with these diffused rectangular 2.5mm x 5mm RGB LEDs with separate red, green and blue LED chips inside! They make nice indicators, and they're fun to color-swirl! Adafruit like diffused RGB LEDs because they color mix inside instead of appearing as 3 distinct LEDs. Pack of 10 Diffused Rectangular 5mm RGB LEDs!
These are Common-Anode type which means you connect one pin to 5V or so and then tie the other three legs to ground through a resistor. Adafruit carry and use CA more than CC because multi-LED driver chips (such as the TLC5940/TLC5941) are often designed exclusively for CA and can't be used with Common-Cathode.