Duplo is a version of Lego bricks from the well known Danish toy company, LEGO Group. Duplo bricks are eight times the size in volume, twice the length, height and width of traditional Lego bricks, and are easier to handle for younger children. Despite their size, they are still compatible with traditional Lego bricks. Since 1977, Duplo has made sets with figures, cars, and houses.
The Duplo product line changes from year to year — even the name Duplo had been dropped twice. Many Duplo sets have reappeared multiple times over the years. The most common sets are the farm, zoo, police station, fire station, airplane, and train sets.
In 1975 Duplo became its own product, with five sets made up exclusively of Duplo bricks. New additions included a round-topped 2 by 2 knob brick and a small 4-wheel wagon with two rows of 6 knobs. This wagon, and its coupler system, is still sold today. With these new Duplo sets, Lego is targeting children 1½ years old with the idea that when the children reach 3 the Duplo bricks can be used together with Lego bricks.
In 1977 the Duplo name was dropped in favor of Lego Preschool. Small figures the size of 2 by 2 knobs were introduced as well. They included a cylindrical head and a tapered body without any limbs (similar in design to Fisher-Price's Little People). Another new brick was a half arch. The new sets included figures, doors, and 2 by 6 knob wagons that could act as a car or train.
The name Duplo was brought back in 1979 along with a new Duplo logo with a rabbit. In 1983, other Duplo figures appeared, often called Duplo people. These figures have a moveable head, arms, and legs and look like large Lego minifigures, but the Duplo people cannot be taken apart for safer handling by small children. Also in 1983, set number 2700 was introduced with a model of a steam engine with two train cars.
In 1986, a Duplo doll house with sliding doors was introduced. This included a Duplo people mother, father, and smaller child.
In 1992, Duplo Toolo was introduced. These used internal screws to stay together.
1993 brought a grey rail train system with a stop and start track. Later, two more train systems arrived. As of 2008, Lego sells Duplo Trains trains in themed Thomas the Train sets as well as two non-themed motorized sets.
The name Duplo was dropped again in favor of Explore in 2002. In the 2004 spring catalog there was a reminder that Duplo was now called Explore, but that fall the well known Duplo name was back yet again with a new rabbit logo.
Lego currently makes Duplo sets licensed with Dora the Explorer, Bob the Builder, and LEGO Duplo Thomas & Friends characters. Duplo sets now include farm, zoo, town, castle, and pirate lines. A doll house and princess castle are available as of 2008.