In general use, herbs are any plants used for food, flavoring, medicine, or fragrances for their savory or aromatic properties. Culinary use typically distinguishes herbs from spices. Herbs refers to the leafy green or flowering parts of a plant (either fresh or dried), while spices are produced from other parts of the plant (usually dried), including seeds, berries, bark, roots and fruits.

In botanical English, the word “herb” is also used as a synonym of “herbaceous plant”.

Herbs have a variety of uses including culinary, medicinal, and in some cases, spiritual. General usage of the term “herb” differs between culinary herbs and medicinal herbs. In medicinal or spiritual use any of the parts of the plant might be considered “herbs”, including leaves, roots, flowers, seeds, root bark, inner bark (and cambium), resin and pericarp.

The word “herb” is pronounced /ˈhɜːrb/ in the UK, but /ˈɜːrb/ is common among North American speakers and those from other regions where h-dropping occurs.

As far back as 5000 BCE, Sumerians used herbs in medicine.[citation needed] Ancient Egyptians used fennel, coriander and thyme around 1555 BCE. In ancient Greece, in 162 CE, a physician by the name of Galen was known for concocting complicated herbal remedies that contained up to 100 ingredients.

Culinary herbs are distinguished from vegetables in that, like spices, they are used in small amounts and provide flavor rather than substance to food.

Herbs can be perennials such as thyme or lavender, biennials such as parsley, or annuals like basil. Perennial herbs can be shrubs such as rosemary, Rosmarinus officinalis, or trees such as bay laurel, Laurus nobilis – this contrasts with botanical herbs, which by definition cannot be woody plants. Some plants are used as both herbs and spices, such as dill weed and dill seed or coriander leaves and seeds. Also, there are some herbs such as those in the mint family that are used for both culinary and medicinal purposes.

A garden of herbs

Herbs have long been used as the basis of traditional Chinese herbal medicine, with usage dating as far back as the first century CEand far before. In India, the Ayurveda medicinal system is based on herbs. Medicinal use of herbs in Western cultures has its roots in the Hippocratic (Greek) elemental healing system, based on a quaternary elemental healing metaphor. Famous herbalist of the Western tradition include Avicenna (Persian), Galen (Roman), Paracelsus (German Swiss), Culpepper (English) and the botanically inclined Eclectic physicians of 19th century/early 20th century America (John Milton Scudder, Harvey Wickes Felter, John Uri Lloyd). Modern pharmaceuticals had their origins in crude herbal medicines, and to this day, some drugs are still extracted as fractionate/isolate compounds from raw herbs and then purified to meet pharmaceutical standards.

Certain herbs contain psychoactive properties that have been used for both religious and recreational purposes by humans since the early Holocene era, notably the leaves and extracts of the cannabis and coca plants. The leaves of the coca plant have been chewed by people in northern Peruvian societies for over 8,000 years, while the use of cannabis as a psychoactive substance dates back to the first century CE in China and northern Africa.

The indigenous peoples of Australia developed herbal medicine based on plants that were readily available to them. The isolation of the indigenous people meant the remedies developed were for far less serious diseases, this was from not contracting western illnesses. Herbs such as river mint, wattle and eucalyptus were used for coughs, diarrhea, fever and headaches.