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

Subject to where you are from, different countries have different terms for "storm drain".
Accordingly to Wikipedia, a storm drain is essentially a tunnel that carry runoffs (rain) from urban areas. For a layman, it helps to think along grating drain of sewage system that operates beneath our cities.
In america, this is often called "storm drain" or "storm sewer".
In great britan, this is also known as "surface water drain" or "surface water sewer".
In Australia and New Zealand, it is also known as "stormwater drain".
And there it is, the next time you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", you now know they mean 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 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 could be a danger to pedestrians. Left uncovered, rubbish will go into the storm drains and cause choking which might eventually lead to flooding.
In order to ensure storm drains serve their purposes while minimizing the risks posed to pedestrians and to prevent choking of the drains, drain covers (gratings) are used to cover the inlets (openings) of the storm drains to achieve two purposes.
Over at Jonite, we concentrate on steel reinforced drain covers (gratings) for your storm drains while preserving the aesthetic areas of the architecture around the drain covers.