The water cycle on this planet is a very important means of life for many life forms, biomes, geological stabilities, and the cleansing of the planet. As the vast majority of the planet is covered in water, there is a specific role water - or the lack of it - provides to everything. Of course, this process can start either over land or at the oceans, but it is better to start with the oceans and finish there.
The Earth's oceans are constantly absorbing, releasing, and distributing heat stored from the sun during the daylight hours. Although it's true that water evaporation occurs at the surface of the world's oceans, the majority occurs near the equator; while lesser amounts are evaporated the closer the water is to each of the poles. Because of this, the water vapor that comes off the surface of the ocean (leaving the salt behind) disperses into the atmosphere, crystallizes at the colder temperatures, and forms clouds. Typically warmer waters are able to produce storm systems much faster than colder waters because of the abundance of rising heat and water vapor.
Heat and Water Distribution:
As storms typically form over the warmer waters, storms follow offshore weather patterns or move along ocean currents. Much like the jet stream in the air, ocean currents are formed by flowing masses of heat upwards, and cold downwards. The Gulf Stream in the Atlantic Ocean flows upwards from the Caribbean, along part of the coast of North America, before crossing the Atlantic Ocean and supplying its warmth to Europe, before cooling off in the Arctic waters, and following a different pattern until it warms again in the waters near the equator. Because of this process of heat distribution and water movement, Europe temperatures are kept more temperate than a much colder Canada, which is at the same latitude.
Due to the Gulf Stream and other such currents around the world, Storms have many warm paths to follow to gain in intensity, or can choose paths of their own, in order to distribute their loads of water on shore.
Evaporated water is brought to the lands via storm systems, and fall to the earth in the form of rain. Because rain falls due to ice crystals overcoming thermal updrafts from a sun warmed earth, rain tends to fall prior to high mountains that are colder, explaining why the side of the mountains facing the ocean is green, and the other side may exist as a desert. Water may also fall as snow and accumulate on mountains and help restore water lost during the summer months, or simply accumulate on the land. Strong summer storms often force large quantities of fresh water far inland, re-supplying water tables under the ground and providing nourishment to animals and plants alike.
Just like the oceans, water can evaporate from rivers and lakes in land, or even from the moisture lost from plants. These new accumulated clouds can carry water even further across the land and rain elsewhere, before leaving the land. However, just because water evaporated as a mostly pure substance doesn't mean it will stay that way.
While in the atmosphere, the ice crystals the make up clouds have a tendency to collect pollutants and other chemicals that are among them. Because the clouds can't do anything but store these impurities, the next rain fall will carry them back to the surface of the planet, possibly hurting plants and animals in the process. These will also get back into the land and to the water collections.
Back to the Oceans:
After water rains back to the land and is collected into underground storages, lakes, rivers, or streams, it will continue a path downhill until it reaches a final elevation with no outlet. While this destination is typically the ocean, it isn't always the case. The Great Salt Lake in Utah is one such place. Water can flow in, but can only leave through evaporation. Because of this, the minerals that are dissolved in the rivers that feed it are left behind, which gives it its salty properties.
Waters that aren't directed into special locations gradually merge into larger rivers until meetings again with the ocean. Water that exits the rivers carry with it various nutrients, particulates, and even contaminants that both feed and hurt ocean life. However, the exchange between sea, land, air, and the journey back is a vital importance.
From here the process repeats.