A tiller, also known as a soil cultivator, is a farming tool used to prepare soil for planting. Gardeners and farmers use a tiller to break up the hardened surface dirt and incorporate organic materials into the freshly turned soil. The first tiller models used human or animal power, but modern tiller manufacturers use gas-powered engines to turn the blades or tines.

It can be argued that the development of the tiller defined the beginning of commercial farming. Early humans may have relied on pre-existing stands of fruits and vegetables or attempted to plant seeds directly into the hardened ground beneath their feet. By creating a simple tiller capable of softening the soil and creating furrows for seeds, the earliest farmers could produce more crops per acre of land.

Most casual gardeners today do not own commercial-grade tillers, but rather rent them by the day or purchase smaller models designed for home use. After the ground has thawed sufficiently in early spring, a farmer or gardener will use a tiller to overturn soil in a predetermined area. Depending on the type of crop, the soil may have to be 'amended,' meaning that acidic or basic fertilizer and organic materials are added to create an ideal balance for the vegetable or fruit to be grown. A tiller can blend these additives into the soil very evenly.

A modern tiller is not the same as a plow, although they perform similar tasks. A plow uses two opposing blades to essentially slice through the soil. A rotary tiller uses two sets of circular tines turned by an engine to cut into the soil to a prescribed depth. These blades are mounted on either the front or the back of the tiller. Front-bladed tillers are recommended for smaller gardens and beginning gardeners. Running a tiller can be like running a floor polisher or sander -- it has a tendency to pull forward, taking the user with it.

A rear-blade tiller is best for larger commercial gardens and experienced users. Different attachments can be used to blend the soil, create planting furrows, build potato hills or even clear snow in the wintertime. Rear-blade tillers reputedly create more even results and are easier to control. However, a rear-blade tiller is significantly more expensive than a front-blade tiller. Either model can be rented for occasional use, but a gardening hobbyist may find that a front-blade tiller is more affordable and does an acceptable job of preparing the soil for planting.