let me know about p-pi-p-pi bond; d-pi-p-pi bond and banana bond?

Dear student ,
Your answer is as follows :
1) p-pi-p-pi bond is when bonding occurs in elements having their vacant place and vacant electron in p orbital. Example : Nitrogen (N2)
2) d-pi-p-pi bonding is when bonding occurs in two elements in which one is having its vacant electron and vacant place in d orbital and other in p orbital.Example : XeO3
3) Banana bond is an extended covalent bond found in boranes in which a hydrogen atom is shared by two boron atoms.It is a form of 3 centre ,2 electron bond.
Example is diborane (B2H2)