Buddhists are both interested and uninterested in cosmology. They are uninterested, first, because all of the distinctions that are typically taken to characterize the cosmos are seen as expressions of utmost ignorance with respect to the true nature of things. For Buddhists, there are no stable, unchanging things; rather, all things are in perpetual flux, and it is only through one's ignorance and desire that one takes them to be substantive and distinct. As this account of their lack of interest in cosmology should indicate, however, Buddhists are also very interested in cosmology, because it is not only the problem but also the solution that is cosmological. Not only can a cosmology constructed through "skillful means" (upaya) illumine the way to overcome ignorance, but overcoming this ignorance is itself adjusting one's understanding of the cosmos.
Thus, Buddhist cosmologies can be, but need not necessarily be, read as objective accounts of the nature of the cosmos; rather, the ultimate aim of these cosmologies is always on the achievement of enlightenment (nirvana), and they must be understood as means to that end. For example, in the Visuddhimagga (Path of Purification), Buddhaghosha (fifth century C.E.) describes the "world" not in detailed spatial and temporal terms but in terms of possible destinations for re-birth: gods, humans, ghosts, and animals, and hell (strangely, the last is a spatial reference, but primarily indicates a realm for tortured souls). Likewise, in the Abhidharmakosha, Vasubandhu (fifth century C.E.) locates a cosmology much like Buddhaghosha's within but one of three spheres (dhatu): the sphere of desire (kamadhatu); beyond this is a sphere of pure form (rupadhatu), and finally a sphere of no-form (arupadhatu). Despite their differences, these two prominent early cosmologies serve as a roadmap for the path to enlightenment, complex enough to exemplify the key points of Buddhist doctrine, yet simple enough to serve as an accessible means for traveling along that path.
Buddhist cosmology becomes inordinately more complicated, however, with proliferation of worlds and Buddharealms. The concept of multiple worlds is already evident in Theravadan literature, where one Buddha oversees many worlds at one time; however, this concept becomes much more prominent in Mahayana texts, where most of these worlds are associated with particular Buddha-realms (buddhakshetra). Each buddhakshetra is overseen by its own fully enlightened Buddha, and is seen as pure, impure, or mixed, depending on the degree of desire and ignorance manifested there. Our own world, Saha, is the buddhakshetra of Shakyamuni (the historical Buddha), and is seen alternately as impure or mixed. Significantly, this association of worlds with different Buddhas is what gave rise to Pure Land Buddhism in the Chinese and Japanese contexts: the so-called "Pure Land," Sukhavati, is a pure world overseen by the Buddha Amitayus/Amitabha (Infinite Life/Infinite Light), and all people who are born into this realm—something attained by faith rather than merit—are sure to achieve enlightenment in one lifetime.
It should be noted that, while Buddhist cosmologies are generally intended to embody the Buddhist path to enlightenment, this does not mean that they do not also draw on the cosmologies of other religious traditions—although this is always done with some modification. For example, Buddhist cosmography, like other Indian cosmographies, is traditionally centered on Mt. Meru, although the cosmography is given a distinctively Buddhist slant by placing the entire world of the living under the dominion of Mara (death). Likewise, the Buddhist notion of cosmic time borrows from the Hindu account of four yugas after which the world is destroyed and formed again; yet this account is again given a Buddhist slant by ridding the process of any creative deities and ensuring that the unenlightened souls are preserved during these recurrent destructions. This process of borrowing and adapting would continue as Buddhism spread into China, Tibet, Korea, and Japan; what would remain constant, however, is the ultimate aim of Buddhist cosmology: namely, enabling those still suffering in ignorance to ultimately achieve nirvana.