A spider bite occurs when a spider pierces the skin with its fangs, injecting venom into the tissues. Most spider bites are harmless and cause only mild symptoms such as redness, swelling, itching, or minor pain at the site. However, bites from certain species—such as the black widow or brown recluse—can produce more serious reactions, including intense pain, muscle cramps, fever, nausea, or tissue necrosis around the bite. Symptoms may appear immediately or develop over several hours. Spider bites typically result from accidental contact when a spider feels threatened, and bites are more common in areas where spiders live or hide, such as basements, attics, or outdoor vegetation.