Spiders, unlike insects, have only two body segments (tagmata) instead of three: a fused head and thorax (called a cephalothorax or prosoma) and an abdomen (called the opisthosoma). Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. Spiders are found all over the world. Spiders show a wide variety of behavior, from the ballet-like mating dances of certain jumping spiders to the seeming athletics of bolas spiders snatching their prey. Most diversity comes with the mode of predation, for example whether the spider waits for it in its orb web, or hunts it down.

Most spiders are unlikely to bite humans because they do not identify humans as prey. Spiders, even small ones, may however bite humans when pinched.

Spider do not intentionally bite or attack human as they do not find them as their prey. They do sometimes bite human when pinched and can leave you with a pain as dangerous as that of a bee sting. So it is better to remove them to avoid any future accidents.

If spiders are present in your area, be very careful when moving cardboard boxes and other such objects that may have become the shelter of a venomous spider. Do not be afraid; but just do not grab a spider.

Generally Spiders are harmless to human, but they are incapable of differentiating their prey. Their sting can cause serious skin disorder and in some cases like if stung by black widow can lead to death.

Types of Spiders  
Black widow spider
Latrodectus tredecimguttatus, known as the European or Mediterranean black widow, the Malmignatte spider, or the Karakurt spider
Red-back spider
Red katipo and black katipo spiders
Button spider
Brown widow spider
Red widow spider
Steatoda — a large genus which includes the false black widows
American house spider

Control & Prevention Tips
Keep your surrounding clean.
Dispose all waste from the premise.
Keep your garden area clean as spiders find these areas suitable to weave their web.
Spraying of insecticides also help in eliminating these pests.
Be very careful when handling trashes or corners not cleaned for a long time.
Seek medical supervision when stung by a spider.
Go for a pest control service to keep a check on the growth of these pests.