Q. Define Keyword and Identifiers?

Keyword:  A keyword is a statement which defines nature of that statement. If statement is a directive then keyword would be the title of that directive whereas if the statement is data-allocation statement then keyword would be a data definition type.

Some illustrations of keywords are: SEGMENT (directive), MOV (statement) etc. 

Identifiers:  An identifier is a name which you apply to an item in your program which you expect to reference.  The 2 kinds of identifiers are label and name.

1.    Name denotes to address of a data item like counter, arr etc.

2.    Label denotes to address of our instruction or process or segment. For illustration

MAIN is the label for a process as below:

  MAIN PROC FAR

                         A20:   BL,45 ; defines a label A20.

Identifier may employ alphabet, digit or special character but it always starts with an alphabet.