1. Scope of Variables

2. Scope
Scope of a variable is the range of statements in which the variable is visible in a program
A variable is visible in a statement if the variable name could be used in the location the statement occupies
Scope rules determine how variable references throughout a program are resolved

3. Static Scope COBOL introduced typed variables with global scope
ALGOL 60 popularized the use of static scoping using begin and end to create blocks of code that could be nested

4. ALGOL 60 Program begin integer x, y; x = 3; printint(x); if (x < 5)
end;
end

5. Dynamic Scoping
Dynamic scoping uses a program call sequence to determine the scope of a variable
{int x = 0;
Define int foo ()
{ return x; }
Define int goo ()
{ int x = 1; return foo(); }
goo();}
Calling goo() with static scoping returns 0
Calling goo() with dynamic scoping returns 1 since a stack is used to maintain the bindings of each variable as a program block is entered