As a subset of the Phylum Gymnosperm, the division of Pinophyta, and in the Class Pinosida, there are four extant (living) Orders: Araucariales, Cupressales, Pinales and Gnetales, and at least three extinct orders: Cordaitales, Palissyales, and Voltziales.

Contained in these four extant orders, there are ten families, about 60-65 genera and some 650 extant species.

All of these six hundred plus species have the characteristics of being: perennial woody plants, most are trees with a few being shrubs, vascular (having a system of channels for carrying fluids, such as sap), cone bearing seed producing and non-flowering

Although the total number of species is relatively small, the class of Pinopsida, commonly called conifers are ecologically important. This is because they are the dominant plants over large areas of land, most notably the taiga (commonly called the boreal and/or snow forest) of the Northern Hemisphere, but also in similar cool climates in mountains further south.

Boreal conifers have many wintertime survival adaptations. The primary adaptations of these northern conifers is there form, which is a narrow inverted conical shape, together with their downward-drooping limbs, all helps them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing.

While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of great economic value for softwood lumber and paper production.

The evergreen tree family of Araucariaceae is one of ten families of conifers. This family has three living genera, Araucaria, Agathis, and Wollemia, of which genera have about 41 species. This family also has eight extinct families. While the native distribution of this family is now largely confined to the Southern Hemisphere, except for a few species of Agathis in Malesia, it was formerly widespread in the Northern Hemisphere during the Jurassic and Cretaceous periods.

Many species of family Araucariaceae are typically extremely tall evergreen trees, reaching 200 fee or more (60 meters). Furtehrmore, they can also grow large stem diameters. For instance, a New Zealand kauri tree (Agathis austrailis) which has been give the name Tane Mahut (The Lord of the Forest) has been measured in at 148 feet tall (42.5 meters) with a diameter at five foot high of 16.11 feet (491 cm). Its total wood volumn is calcuaated to be 18,250 cubic feet, (516.7 cubic meters), making it the third largest conifer after Sequoia and Sequoiadendron, both of which are of the Cupressaceae subfamily Sequoioideae.

Like all conifers, this family produce cones bearing seeds. Each tree can have both male and female cones (monoecious) or they can have only male or only female cones (dioecious)

Male cones are among the largest among all conifer cones, on average. They are cylindrical and drooping, somewhat resembling catkins. They are borne singly on the tips of branches or the axils of leaves. They contain numerous sporophylls arranged in whorls or spirals. Each has four to 20 elongated pollen sacs attached to the lower surface at one end. The pollen grains are round and do not possess wings or air sacs

Female cones are also very large. They are spherical to ovoid in shape and borne erect on thick, short shoots at branch tips. The numerous bracts and scales are either fused to each other or separate for half of their lengths. The scales almost always bear only one seed on its upper surface, in contrast to two in true pines (family Pinaceae). The cones are very large and have some of the largest seeds among conifers. They are dispersed by wind, usually using wing-like structures. On maturity, the female cones detach and fall to the ground. Due to their size, they can cause serious injuries if they hit a person.