There are at least 25,000 species of orchids.

8% of all flowering plants are orchids, making them the largest family.

Orchids are nearly cosmopolitan, but the majority of species are found in the tropics and subtropics, ranging from sea level to almost 5000m in nearly all environments except open water and true desert. In places they are dominant, particularly in nutrient-deficient habitats. Over half of the species are epiphytic.

Their life cycle is complex, often involving a fungal partner (mycorrhiza), at least for germination, and specific pollinators. Therefore, they offer much in the study of the interactions of plants, fungi and animals.

Many are extremely sensitive to environmental changes, a subject of increasing concern at present.

Phylogenic and evolutionary relationshipshave been studied intensively using DNA sequences and other data, leading to a much increased knowledge of the family.

It is a family of considerable economic importance, particularly in horticulture and floristry, but also increasingly in the pharmaceutical and fragrance industries. Orchids are a major source of income in some countries.

Orchids are a charismatic group and have been called the "pandas of the plant world". They are a prominent focus of plant conservation. All appear on CITES Appendix I or II. Many nature reserves exist because of the orchids that occur there.