What is BCP? When does it used?

The Bulk Copy Program (BCP) is a command line utility which comes with Microsoft SQL Server. it is used to Import or Export data from SQL Server database.
BCP is a case sensitive command line. If user mistakes with args then result will fail.
BCP command syntax

bcp {dbtable | query} {in | out | queryout | format} datafile

[-n native type] [-c character type] [-S server name] [-U username]

[-P password] [-T trusted connection]