PowerShell How To Join / Concatenate Strings

Two strings that we would like to join or concatenate.

$a = "test1" 
$b = "test2"

Concatenate and output two strings saved as variables:

$a + $b

Concatenate and output three strings ( 2 variables and one literal ):

$a + " " +  $b

Same except save these to a variable and output that:

$c = $a + " " +  $b
$c

PowerShell Join Strings

Join two strings each on a separate line:

-join $a, $b

Join two strings on the same line ( no space ):

-join ($a, $b)

Join three strings ( 2 variables and one literal ):

-join ($a, " ", $b)