what is allyl compound?Pls explain in detail

All those compounds which have universal allyl group i.e. unsaturated C₃H₅ group (derived from propylene), are called as allylic compound.
The allylic group is : {CH₂=CH-CH₂-}
So, the example as of allyl compound is like allyl bromide , CH₂=CH-CH₂-Br