String concatenation is the joining of two series of characters, or strings. The characters can be alphabetic, numeric, special characters or a combination thereof. Concatenation is language dependent and may have different operators depending on the computer programming language used.
Example
a = "this is"
b = "my name."
print ab
printed > this ismy name (note no space between is and my )
print a + b
printed> this is my name ( the + operator joins the strings with a space between them. )