Subject to 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 actually a tunnel that carry runoffs (rain) from urban areas. For a layman, it helps to think along the line of sewage system which works beneath our cities.
In the states, this is actually best known "storm drain" or "storm sewer".
In the united kingdom, this is best known "surface water drain" or "surface water sewer".
In Australia and New Zealand, it is popularly known as "stormwater drain".
And there it is, the very next time you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", congratulations, you know they refer to 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 counteract flooding.
Although storm drains perform a amazing job of draining excess water from tree grate , the inlets are essentially openings where left uncovered could be a hazard to pedestrians. Left uncovered, rubbish will enter the storm drains and cause choking which can eventually end up with flooding.
To guarantee storm drains serve their purposes while minimizing the potential 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 the two purposes.
Over at Jonite, we specialize in steel reinforced drain covers (gratings) that cover your storm drains while preserving the aesthetic elements of the architecture around the drain covers.