Social Media scheduling is simply the automation of delivering social media content in advance, so it goes out a pre determined time.
It's a great tool, and there are various 3rd parties out there such as Klout that will do it for you for free.
But if you do schedule your content, don't make the mistake Apple did recently when scheduled a post from the late Joan Rivers endorsing their new iPhone product 
It seems a commercial deal was agreed shortly before her death and her social media manager scheduled some content far in advance to coincide with Apples product launch.
Cue an embarrassing endorsement from the grave! Could go into the marketing fail/marketing genius category, but I think in this case it is a genuine embarrassing cockup and the posts were very quickly pulled.
image credit: www.tmz.com
So scheduling your social media is a great marketing tool, but don't schedule too far ahead! 
