How come in VB it uses += for text and numbers?

Example:

Dim i as integer

i+=1

Also

Dim s as string

s+="asd"

Shouldn't it be

s&="asd"

I mean for continuity sake? i've always been taught not to use the "+" sign to add strings... it seems very odd.


Or am i completely wrong about the sign? This is what i've seen in a book i'm learning from.