what is a delta

A delta is a landform shaped like a triangle that forms at the mouth of a river as it flows into a lake or the sea, by the deposition of sediment carried by the river. Deltas are wetlands that are usually fertile agricultural areas due to the rich accumulation of silt. The term delta comes from the upper-case Greek letter delta (Δ), which is shaped like a triangle. There are different types of deltas, such as arcuate deltas, which have a triangular or fan shape, and cuspate deltas, which are more pointed and tooth-shaped. The worlds largest delta is the Ganges–Brahmaputra delta in India and Bangladesh, which empties into the Bay of Bengal. In addition to its geographical meaning, the term delta can also refer to a change in a figure or amount, the measurement of how the price of an option changes compared to the price of the shares, etc. that it is based on, or a fourth position in the structure of an organic molecule from a particular group or atom.