I see those commonly around where I live. I can't tell you for certain without a picture but I can tell you the most common black spider with yellow on its back and legs (sometimes different patterns) is the Banana Spider. As far as I know I believe it IS poisonous. If you see one then either leave it alone, or kill it from a distance. (I'd prefer something hard like a shovel. I wouldn't even attempt a spider spray because it's likely not to work because of it's size and if it DID work you would PROBABLY be using ALOT of it. Be easier and cheaper just to pulverize it from a distance.
a tranchila
I believe this spider friend of yours is a jumping spider, although there are lots of other spiders out there who are yellow, grey, black, orange and brown.
a little spider black legs and yellow back with black spots
Argiope aurantia is a black spider with yellow stripes. Its common names join such different physical descriptions as black and yellow garden spider, corn spider, writing spider, and zipper spider. The black and yellow garden spider generally may be considered harmless to humans.
It's a perfectly harmless (and beautiful) ARGIOPE spider. Also called the black and yellow garden spider, banana spider, or corn spider.
A yellow pecked moonlight named sunshine! Luv Alexis + mib Lopez
its a leaping spider i think
This has to be the yellow and black red spotted spider.
Jumping spider
That is a garden spider
A black spotted yellow spider that just ate a gumball.
Garter spider
A black spider with yellow stripes is a garden orb spider. These are very common and not poisonous to humans.