Delimiters : Introduction « PL SQL Programming « Oracle PL/SQL Tutorial

A delimiter is a simple or compound symbol that has a special meaning in PL/ SQL.

+, -, *, /Addition, subtraction/negation, multiplication, division
%Attribute indicator
'Character string delimiter
.Component selector
(,)Expression or list delimiter
:Host variable indicator
,Item separator
"Quoted identifier delimiter
=Relational operator
@Remote access indicator
;Statement terminator
:=Assignment operator
=>Association operator
||Concatenation operator
**Exponentiation operator
<<, >>Label delimiter (begin and end)
/*, */Multi-line comment delimiter (begin and end)
--Single-line comment indicator
..Range operator
<, >, <=, >=Relational operators
<>, '=, ~=, ^=Different version of NOT EQUAL

24.1.1.Writing a simple program
24.1.2.Each complete line of the PL/SQL code must end with a semicolon (;).
24.1.3.Anonymous Block Structure
24.1.4.An example of an anonymous block.
24.1.5.Anonymous blocks can be nested in the procedure and exception blocks in as many levels as you want
24.1.6.The Lexical Set of Elements
24.1.9.Multi-line comments start with /* and end with */.
24.1.10.Declaring variables
24.1.11.Declaring a Variable by Reference
24.1.12.There are some restrictions on the declaration of variables:
24.1.13.Assigning values to variables
24.1.14.Assign SQL query results to PL/SQL variables
24.1.15.Literals as variable values
24.1.16.Examples of Integer and Real Literals
24.1.17.Numeric literals cannot contain dollar signs or commas, but they can be written in scientific notation
24.1.18.Character and string literals in the Oracle world are enclosed by single quotes