I do not think it is a spider (Arachnid) (8 legs). I think it is an insect (6 legs). It can JUMP very high and far. They are scary- sometimes grey colored to blend in to backgrounds, difficult to catch/kill - They live in cool dry places and are seen in the Summer and Spring. They are found under decks and in basements. I can not look this up on the internet as the pictures would scare me. :)
trantula
A brown recluse. If you happen to get bitten by one, call 911.
An Arrowhead spider is brown with a green back. This spider is also known as a Triangle Orb Weaver. This spider is not venomous.
The brown recluse spider is the kind of spider that has a brown oval mark on its back. This spider's bite is extremely deadly to animals and humans.
They are called White-Spotted Brown spiders
Brown Rectcluse Brown Rectcluse
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A Garden Spider
The spider that is black with a white crescent on its back is the Brown House Spider. This spider is often confused with the red-back spider.
Is it a white orb? In that case it would be an egg sack. If it is actually a white spot it cold be a wolf spider. I am sure another user could provide a more detailed answer but I have seen wolf spiders with white spots.
The worst kind.
a tarantula!
a redback spider
A garden orb weaver probably