The word trowel comes from the Latin word "truella", meaning "small ladle". Gardening trowels have a scooped cross section to enable them to carry soil without spillage. They are an indispensable tool for planting and weeding.
There are variety of different shapes and sizes of trowel on the market suited to different functions. Narrow trowels are used for transplanting and weeding. Trowels with a pointed blade will perform better in harder soils.
Some trowels have a handy depth gauge incorporated into the blade to help the gardener accurately measure how deep they are planting.
A long handle will improve the reach of the trowel. Long handled trowels are useful for gardeners who want to avoid kneeling. However, it is important to avoid the temptation to bend from the hips when using a trowel - this is a sure recipe for back pain. Lighter trowels are often more ergonomic as they put less strain on the wrists.
It is well worth investing in a high quality trowel - even top of the range trowels are not expensive. Avoid stamped metal trowels - these cheap tools have a short life-span. They will bend or the joint between the handle and blade will become loose. Good quality trowels have a carbon steel blade solidly fixed to an ash or hickory handle. A stainless steel blade (carbon steel with chromium and nickel added) has the advantage of being rustproof.
There are also some decent aluminum trowels on the market. Aluminium trowels are cast in one piece so there is no need to worry about whether the blade is sufficiently anchored in the handle. Aluminium will not rust but it is not as strong as steel and does not support a good cutting edge - aluminium blades loose their sharpness and are prone to chipping in rocky soils. There are one-piece trowels on the market with rubber or plastic coated handles to protect the gardener from the cold feel of a metal handle.
Gardening trowel with plastic coated handle