What is the difference between implicit and explicit cursors

The implicit cursor is automatically declared by Oracle whenever a SQL statement is executed.
An implicit cursor is used to process the instructions INSERT, UPDATE, DELETE, and SELECT INTO. During processing of an implicit cursor, Oracle automatically performs operations OPEN, FETCH, and CLOSE.

An explicit cursor is used for queries that return more than one registration. An explicit cursor is declared and called by the programmer and is used by means of specific instructions in PL / SQL.