There is no clear universally accepted definition of organic farming. However, we can look at some various ideals surrounding the term organic farming.
In general, most consider organic farming a specific production system which aims to avoid the use of synthetic and harmful pesticides, fertilizers, growth regulators and livestock feed additives.
Almost all organic farming systems rely on what some call, "Alternative farming methods" such as crop rotation, mechanical cultivation, animal manures, green manure and integrated pest management to maintain healthy soil, grow healthy plants and to control pests and weeds. The kicker is that these alternative farming methods are older, from a historical perspective, than newer farming methods that include using pesticides and other synthetic farming applications.
In the USA, the National Organic Program (NOP) provides the most commonly used definitions of organic farming. That said, USDA organic farming standards don't truly cover the maximum in sustainable farming practices. Some feel that organic farming methods should include sustainable practices, while some argue that sustainability is not a necessary component of organic farming, thus the non-universal acceptance of a clear organic farming definition.
Numerous U.S. states, regions and local farmers have additional organic farming standards in place that exceed basic NOP standards. Additionally, other countries have their own established organic farming standards that differ from USA standards.