Symbiosis is the scientific term for two (or more, but generally limited to two) organisms that live together in union to help one another. Although the symbiotic union is not always advantageous the majority of symbiotic unions either help both organisms or leave one unaffected while one is benefited. Symbiosis can be broken into two different types. There is ectosymbiosis which is the organisms living on the outside of each other. Such as bugs on plants. The other is endosymbiosis which is when one organism lives within the cellular structure of a larger organism. 
Types of Symbiosis
There are more than one form of symbiosis. Each different type describes a distinct way the organisms interact with each other. However, some of these symbiotic relationships have been put under question on whether they actually describe symbiosis or just a close relationship in an ecosystem.
Mutualism is an example of a more or less perfect symbiotic union. In mutualistic symbiotic unions both organism are benefited and neither organism is harmed in any way. Most of these relationships are ectosymbiotic.
Some examples of a mutualistic relationship are bees and flowers and certain ants. Bees create this relationship because they cross-pollinate the flowers allowing the plant to produce fruit and ultimately offspring. In return the bees are able to acquire the nectar from the plants which they use for food and to develop their hives.
Another example is that of certain plants, such as legumes, that perform nitrogen fixation with the aid of bacteria. The bacteria changes the nitrogen into a usable form for the plant and also gives off amino acids that benefit the plant, and the plant allows for the bacteria to be protected within its roots.(Purves 722-723)
- Main Article: Commensalism
Commensalism is a symbiotic relationship where one organism is benefited whereas the other organism is not affected for the better or worse. The best example of this symbiotic relationship is between the Clownfish (Amphiprion ocellaris) and the Ritteri sea anemone (Heteractis magnifica). In this relationship the Clownfish lives within the sea anemone. It is therefore protected by the anemone because of the anemone's stinging tentacles. The clownfish has a particular secretion on its body which allows it to pass through the anemone unscathed. In this relationship the clownfish benefits because it has a safe home whereas the sea anemone gains nothing. 
- Main Article: Parasitism
In a parasitic symbiotic relationship only one of the organisms benefits. One organism will benefit with nutrients and protection whereas the other organism will be harmed by the symbiotic relationship. This form of a symbiotic relationship has been a controversial idea because some scientists do not find it to actually be symbiotic but rather survival of the fittest. Some examples of this type of symbiosis are ticks, leeches, mites, and aphids. All of these organisms feast on their host, gaining nutrition from them, but giving nothing back in return. (The Americana Encyclopedia: Symbiosis)
- Main Article: Endosymbiosis
Endosymbiosis is a form of symbiotic relationship wherein an organism lives in the body or cell of another. These organism, which are known as endosymbionts, may either occupy the intracellular space or live extracellularly.
The relationship is usually mutually beneficial, and often in some cases obligate so that neither are able to live without the other. The acquisition of an endosymbiont can result in the production of unique and important abilities or structures in the host organism. Well known examples include the nodules formed by the nitrogen-fixing bacteria that inhabit legume root cells, or the dinoflagellate that live within stony coral.
Symbiosis in Today's Culture
Symbiosis has been shown in culture more than most realize. Hollywood is one of the prime examples of this. Most scary movies or horror movies deal with some type of symbiotic relationships. The Alien movies all deal with a symbiotic and alternation of generations relationship. Most horror movies that deal with some type of parasite are relating to a parasitic symbiotic union. Another example in Hollywood is that of Finding Nemo. In this movie, the main character Marlin lives in a sea anemone. They also explain in the movie why the Clownfish is not affected by the sea anemone. This relationship is a commensalistic relationship. Outside of Hollywood, the villain Venom in Spiderman is a symbiotic alien. His relationship with the hero Spiderman is a mutualistic relationship, because they both benefit from the union. However after awhile the union becomes a parasitic symbiotic relationship when Venom tries to overcome Peter Parker (Spiderman). The last example of a symbiosis in culture is that of marriage. Marriage has been attributed to a symbiotic relationship by the pastor Mark Driscol from the church Mars Hill. He has stated that the union of a man and a woman is a symbiotic union because it is bringing two people together to complete one another. This relationship would be a mutualistic symbiotic union. 
- Purves, William. Life the Science of Biology. 2005. Couriers Company Inc.
- The Americana, 1910, Frederick Converse Beach, Symbio'sis
- Symbiosis Wikipedia
- Parasitism Wikipedia