string1 + string2

The concatenation operator takes two string variables and returns a string made of sticking both strings together.

Multiple concatenations per line are supported, and the strings can include string functions such as LEFT, RIGHT, HEX and STR.  Also if a constant or integer is used it will be automatically converted to a string, as if it had been enclosed in a STR().

DIM A$(20)
DIM  B$(20)
DIM  C$(30)

A$="Hello,"
B$=" World!"
C$=A$+B$
PRINT C$
SLEEP

The output would look like: