Oracle has two commonly used data types for character, those are CHAR and VARCHAR/VARCHAR2.
CHAR data type
‘CHAR’ data type used for fixed-length character data of length size bytes.
The Maximum size of CHAR data type is 2000 bytes or characters.
The default and minimum size of CHAR data type is 1 byte.
VARCHAR or VARCHAR2 data type
Oracle comes with VARCAHR or VARCHAR2 data type for variable-length character string having maximum length size bytes or characters.
The Maximum size is 4000 bytes or characters for VARCHAR or VARCHAR2 data type.
The Minimum size is 1 byte or 1 character.
You must specify size for VARCHAR2 data type.