The Linac Coherent Light Source (LCLS) was designed to generate X-ray pulses a billion times brighter than anything before, producing high energy X-ray pulses that would last for femtoseconds, millionths of a billionth of a second. The US Dept of Energy invested in LCLS and in April 2009, after more than a decade of development, SLAC made history when the first light from LCLS was produced. See the 10 areas where LCLS has pushed boundaries.