The Happy99 worm, also known as Ska or i-Worm, was a worm for Windows, appearing in 1999. The worm would display a gif of exploding fireworks in a window titledย โHappy New Year 1999!โณ. This was the first worm known to spread via e-mail and usenet. Other than attaching itself to the userโs computer, this worm did no damage.