It can just be a red back spider...
a wolf spider. they hurt but are not deadly to humans
A spider.
It is a type of house spider, likes dark places like cellers, attics e.c.t... And will eat any type spider if it is hungry, and will also eat its own kind if no food is found hope that answers your question.
a red back.
A black widow spider is black with a red mark on it's abdomen; this might or might not be what you meant. The black widow sometimes has a red mark on her back, as well. The red backed spider of Australia, a relative of the black widow, has an orange red mark on the back.
red back spider
a spider.
red back
Arachnic
Have seen a very small spider with 4 white dots and 1 red dot. Not a red back. Ta ~Snaff
The distinctive feature of a red spider with a yellow back is its unique coloration, which sets it apart from other spiders.