BDC stand for (Batch Data Communication) and it is a batch interfacing technique which is used in SAP developed and mainly used for uploading data into the SAP R/3 system. BDC works by simulating the user input from transactional screen via an ABAP program. It also allows you to perform database updates in the background using standard SAP transactions and the resultant entries will be as if the user had manually entered the data via SAP means that you do not bypass any of the standard SAP consistency checks, authorisations etc.