What is symbiosis? what are the three major types of symbiosis?

Symbiosis is the relationship of 2 organisms. The 3 major types are commensalism, mutalism, and parasitism. Hope that this helps!

Symbiosis is close relationships between species.
The three types are Mutualism, Commensalism, and Parasitism.

Mutualism is a symbiotic relationship in which both organisms are helped.
For example, butterflies and flowers. The butterflies get food and the flowers get pollinated.

Commensalism is a symbiotic relationship where one organism benefits whilst the other remains unaffected.
An example of this is remora and sharks. Remora attach themselves to the sharks to protect itself and to get food by eating the leftovers of what the shark has eaten. Meanwhile, the shark doesn't care. It isn't hurt but it isn't harmed.

Parasitism is a symbiotic relationship in which one of the organisms benefits by harming the other.
An example of this is ticks and dogs. The ticks gain nutrients by taking nutrients from dogs (and other animals). The ticks are helped and the dogs are harmed.