what are wraps???

Being new to the forum and IP world, Ive managed to work out several accranyms and trying to understand some different investing ideas. But can someone put me out of my missery and explain what a "wrap" is please......!:)
Head over to www.positivecashflow.com.au
They have a 5-part wrap course which you can do through email for free.
I found it very good and it's aimed at people new to wraps.