Preventing Auto-Sync on One-Off Basis for an iPad, iPod or iPhone

Most of time you want automatic sync to run when you plug your iPad, iPod or iPhone into your computer. Indeed, this is the default setting in iTunes for all three devices.
However, sometimes you just don’t want to sync your iPad, iPod or iPhone when you connect it to your computer. Here is a simple trick to prevent aauto-sync from running on a one-off basis: With iTunes open, hold down Shift+Control on a PC or Command+Option on a Mac while plugging your device in. Doing this will make iTunes skip the automatic sync just once.
And note as well, you can prevent automatic syncing from running on a default basis for any specific iPod, iPhone, or iPad; or for all iPod, iPhone, or iPad devices you connect to your computer. See this Apple Support article for instructions on doing this.