What is a Siding used for in railroad terminology?

A siding is a secondary track that runs parallel to the main track and is primarily used for the purpose of meeting or passing trains that are on the main track. This function is essential for maintaining the flow of rail traffic, as it allows one train to move aside and let another train pass without causing delays. By using the siding, trains can efficiently share the main line, especially in cases where there is only a single track available for two directions of travel.

While sidings may occasionally serve other purposes, such as temporarily holding trains that are not currently in service or allowing work to be conducted on the main track, their principal design and operation focus on facilitating the safe and effective passing of trains. Thus, the option highlighting their role in meeting or passing trains accurately reflects the primary function of a siding in railroad operations.