Depending 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 Jonite Stone Gratings .
Accordingly to Wikipedia, a storm drain is largely 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 typically referred to as "storm drain" or " Jonite drainage grating .
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, when you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", you now know they talk about 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 protect yourself from flooding.
Although storm drains perform a amazing job of draining excess water from the urban areas, the inlets are essentially Jonite trench grates where left uncovered can pose a hazard to pedestrians. Left uncovered, rubbish will go into the storm drains and cause choking which can eventually trigger flooding.
In order to guarantee storm drains serve their purposes while minimizing the dangers 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 specialise in steel reinforced drain covers (gratings) which cover your storm drains while preserving the aesthetic aspects of the architecture around the drain covers.