Many of today's steam trains might be considered as real ones as well, providing they are not strictly scale or not enough detailed ones in favor of a robustness appropriate for children or an inexpensive production.

Some similar but larger vehicles are made for children to ride in, typically in parks and playgrounds; often they run on tires and not tracks.

The first widely adopted standards for toy trains running on track were introduced in Leipzig, Germany in 1891 by Märklin.

Most of these standards never really caught on, due to their large size, which made them impractical to use indoors, as well as the high price of manufacturing.

Another size that is attracting interest among hobbyists is building and operating trains from Lego, or L gauge, which is roughly 1/38 scale.

The same "gauge" is used by the "Lionel Great American Adventure series" produced by Learning Curve, the Plarail system from Tomy and Trackmaster.

The elements are very simple in design, sturdy and washable as they are thought for play including such environments as sandboxes, mud and water.

However, most engaged in a practice of selective compression in order to make the trains fit in a smaller space, causing the actual scale to vary, and numerous manufacturers produced 1:64 scale trains—the proper size for S gauge—in O gauge, especially for cost-conscious lines.

Around 1875, technological advancements in materials and manufacturing allowed tin to be stamped, cut, rolled, and lithographed faster than ever before.

[2] Toy trains were revolutionized when Märklin, a German firm that specialized in doll house accessories, sought to create an equivalent toy for boys where a constant revenue stream could be ensured by selling add-on accessories for years after the initial purchase.

[citation needed] Electric trains followed, with the first appearing in 1897, produced by the U.S. firm Carlisle & Finch.

[citation needed] Today, S gauge and O gauge railroads are still considered toy trains even by their adherents and are often accessorized with semi-scale model buildings by Plasticville or K-Line (who owns the rights to the Plasticville-like buildings produced by Marx from the 1950s to the 1970s).

[citation needed] Many modern electric toy trains contain sophisticated electronics that emit digitized sound effects and allow the operator to safely and easily run multiple remote control trains on one loop of track.