What is catenary?

[Voice From Beyond]

What does the catenary function do on the track build menu?

[Raspina]

It puts catenary (=electricity) on your rails, which is needed by modern trains.

[Mansen]

Additionally any electric train needs it ALL of the way on any line it takes - It can't be without for even a meter (You usually have to hunt down a free Caternary-less spots near switches and stations)

[Voice From Beyond]

Ok that makes sense. My dictionary had this definition:

"The curve assumed approximately by a heavy uniform cord or chain hanging freely from two points not in the same vertical line"

[GeneralGeldenhuys]

Ugh, whaaaat?! Catenary is overhead wires in simple railway terminology. You also get 3rd rail which gives electricity to locomotives. Usually the norm today is to use 25kV AC power, but in the old days it was usually 3kV DC power. Other power solutions are also available.

[Mansen]

It's all about the context. :)