Request for proposal ( RFP, sometimes called request for tender )
RFPs request a detailed proposal on how the work will be
accomplished, who will do it, résumés, company experience,
price, etc.
Type of contract: CR(Cost reimbursable)
Invitation for bid ( IFB, or request for bid, RFB )
IFBs usually just request a total price to do all the work
Type of contract : FP (Fixed Price)
Request for quotation ( RFQ )
RFQs request a price quote per item, hour, meter,
or other unit of measure.
Type of contract : T&M(Time and Materials)
Request for Information(RFI)
As one of the types of procurement documents, but in reality,it
does not belong in this category. A procurement document is an
attempt to procure something, while and RFI is simply looking for
Information.