Apple iPhone in 2007 that put the nail in the coffin for the Palm Treo. Palm came back in 2009 with the launch of webOS and the Palm Pre. Widely expected to challenge the iPhone for smartphone supremacy, a lack of apps and a confusing ad campaign did in the Pre and by the end of 2009 it was the Motorola DROID and Android that was giving the iPhone its first dose of competition.
Eventually, HP purchased Palm but could not do any better with its version of the Palm Pre. The webOS flavored HP TouchPad tablet also flopped and the Palo Alto company ended up selling webOS to Korean manufacturer LG, which will use it in its next generation of television sets.
source: Macotakara (translated) via AppleInsider