Purchasing through tendering is most common in government and public sector buying where besides restricted expenditure on buying transparency in the buying process also is important.
Tender basically is the quotation submitted by the interested vendors against Tender notices which are invitations extended to the prospective vendors to quote for the given material.
depending upon situations, tendering too has various modes that is types.
Open Tender : In a situation where the sources of supply that is vendors are not known or there are likelihood of getting more responses from unknown sources then Open tendering is resorted to.
This is done through large scale reachable media such as Internet, Newspapers or leading trade journals.

Global Tender : Global tenders are open tenders with global reach. Even international vendors may like to quote
Limited Tendering : These is the mode employed when the sources of supply are fully known. Through letters etc , usually known as Tender enquiry or Invitation to tender , the quotations from the short listed vendors are requested for.
Once the tenders or quotations are received , their technical as well as commercial evaluations are done. Based on such Techno-commercial suitability of tenderers the lowest price offered tender is accepted for placement of order.

During the course of offer evaluation , many rounds of negotiations are usually held to firm up terms and conditions and prices etc.
Tender buying is very popular and perhaps the only mode of buying in government sector. Even in Private sector such a procedure is adopted if the monetary value involved is appreciably high.
Now a days, for generating genuine competition among the tenderers negotiations are not encouraged and the orders are placed necessarily on the lowest price offered supplier..