Based on where you are from, different countries have different terms for "storm drain".

Based on where you are from, different countries have different terms for "storm drain".
Accordingly to Wikipedia, a storm drain is largely floor drain cover that carry runoffs (rain) from urban areas. For a layman, it helps to think along the line of sewage system functions beneath our cities.
In the states, this is actually best known "storm drain" or "storm sewer".
In the UK, this is typically referred to as "surface water drain" or "surface water sewer".
In Australia and New Zealand, it is commonly known as "stormwater drain".
And there it is, when you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", you now know they talk about exactly the same thing.
Functions of storm drain include draining excess water (rain or storm water) and ground water from pavement, streets and carparks into rivers and streams in order to avoid flooding.
Although storm drains perform a amazing job of draining excess water from the urban areas, the inlets are essentially openings where left uncovered can pose a danger to pedestrians. Left uncovered, rubbish will go into the storm drains and cause choking which may eventually trigger flooding.
In order to ensure storm drains serve their purposes while minimizing the potential risks posed to pedestrians and to prevent choking of the drains, drain covers (gratings) are employed to cover the inlets (openings) of the storm drains to achieve the two purposes.
Over at Jonite, we concentrate on steel reinforced drain covers (gratings) that cover your storm drains while preserving the aesthetic aspects of the architecture around the drain covers.