G-scale is a scale for model railways, and the most popular scale for garden railways - indeed this explains the name. Most models maufactured in Europe are to a scale of 1:22.5, although models made in the USA are usually to a slightly smaller scale.
The major European manufacturer, and the one that really made garden railways popular, is Ernst Paul Lehman Patentwerk, and is sold under the brand name of LGB (Lehmann Gross Bahn or Lehmann Big Train). The company was founded in 1881 and started producing LGB in 1968. Today it produces models of European and US originals, of steam, diesel and electric prototypes as well as a large range of coaches, trucks and accessories.
LGB track is made of brass and so can remain outside in all weathers - a quick wipe and it is ready for use. It is so strong that an early advertisement demonstrated an elephant walking on it but causing no damage.