Is it a weed?

This is Lamium, commonly known as deadnettle, not sure of the full name, but it does tend to pop up and most of us treat it as an unwelcome invader. There are much nicer forms of Lamium (i.e., L. White Nancy) which will grow happily in shade as long as its not bone dry.

I have this dead nettle with purple flowers its lovely but tend to agree with Bamboo there are prettier ones out too.

Bees love them,mine has beautiful white stripes going through the leaves, which are heart shaped

and best of all it doesnt sting

x x x

I grow this dead nettle in a tub it also has purple flowers and no sting.It has flowered on and off all summer.

Thanks to you all. Maybe I'll move it to a tub, as you say it is quite pretty.