Black Widow
i think a black widow
A black spider that has a red stripe on the back is possibly a red spotted ant mimic spider. They walk on six legs instead of eight and can be found in Arizona.
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.
a red back looks almost the same. But doesnt have an hourglass shape. It has a red stripe on top of its abdomen.
A RED BACK!!! bY THE WAY I WOULDN'T TOUCH IT!! THEY ARE REALLY DEADLY, ESPECIALLY THE BABY ONES!!! ^ i wouldn't pay attention to that If the red is on the belly then worry more, it the red is on the back its not a black widow, ive seen a bunch of spiders with a black body and white stripe, they are jumping spiders, the red button i don't know much about.
The Red-back spider (Latrodectus hasselti) is commonly found in Australia. They are a small black venomous spider with long thin legs, and the females have a red stripe on their globular abdomen.
A garden spider, if it looks like this: http://i.pbase.com/v3/48/95248/1/48116303.GardenSpider5.jpg. Apparently a Argiope aurantia. We have them all over the place here and I've never heard of them being dangerous.
This is probably a Red-Backed Jumping Spider. The male has a black body with a bright red abdomen. The female is the same, but the red abdomen has a black stripe. They're found all over the United States. If you want pictures of them, you can find them online at http://kaweahoaks.com/html/spi_phidippus_johnsoni.html.
A black spider with a red back and thick fuzzy legs is commonly called a jumping spider. The formal name is Phiddipus audax.
Black Widow
The Two Step Spider, or Jockey Spider, is actually a reference to the Redback Spider which is indigenous to Australia. They look much like a Black Widow with an hourglass underbelly but the females also have a red stripe across the backside. -Joe There is a spider that can turn into a banana but no two step spider.
This is the rarely seen phahlenderthemterghityfalogal spider if you see on you are 1 in a million no photos have been released due to the nature of the spiders that stay away from humans.