As this blog says, the semicolon has been introduced as the "statement separator" in December 1958, in the report about the language IAL (International Algebraic Language), which has been rebranded later, in 1960, as ALGOL.<p>The next important point in its history is in the language CPL (in its version described in January 1966), where the statement separator could be either the semicolon or the new line, whichever was convenient.<p>This feature of CPL has been inherited by the UNIX shell and by many other programming languages where the semicolon is used only for writing multiple statements on a single line.<p>While most such languages use some special character to mark continuation lines, to allow multiple-line statements, the CPL compiler was more clever and it decided automatically when a statement could not be terminated at the end of a line, so that the next line must have been a continuation line.