Series vs Parallel

• paralles - current is devided
• series - voltages is devided

Schematcis with breadboard examples

• LEDs in Series - http://www.sysrecon.com/tag/led/
• LEDs in Parallel - http://www.techdose.com/electronics/Wiring-Multiple-LEDs/226/page3.html

LEDs with 555 Timers

http://circuitdigest.com/electronic-circuits/heart-shaped-serial-led-flasher

http://circuitdigest.com/electronic-circuits/fading-led