Parasitic plants, represented by 4200 species, are ubiquitous in both natural and managed ecosystems. They acquire some or all of their water, carbon and nutrients by attaching to host roots or shoots using specialist structures known as haustoria. Most of them belong to the families of Orobanchaceae, Loranthaceae, Santalaceae, Viscaceae and Cuscutaceae. Some of the parasitic plants are pathogenic angiosperms, and their parasitic behaviour can drive changes in the biotic and abiotic factors and thereby exert strong impacts on the structure and function of ecosystems. Parasitic plants can uptake nutrients from their hosts, change the quality and quantity of litter, consequently influencing soil physical and chemical properties. Parasitism can drive the growth and turnover of host roots, change the pattern of root exudation, change the carbon and nitrogen input into the soil, consequently changing soil physical and chemical properties. The high transpiration rate of parasitic plants can change the soil water potential. Plant parasitism can also change the atmospheric CO₂ and temperature. Parasitic plants can alter their hosts' behavior, which can lead to changing interaction and competition between the host and the non-host species, thereby affecting the community structure, biodiversity and succession. Plant parasitism can reduce or increase ecosystem productivity dependent on the community traits and environmental conditions. Parasitic plants and their hosts can be consumed by herbivores including plant-feeding insects, consequently affecting the consumer behavior and consumer community structure. Plant parasites and non-plant parasites may share the same hosts and therefore they may compete with each other for host resources. Such interaction can directly or indirectly also affect other parasitic plants or pathogenic fungi. Parasitic plants can alter soil biogeochemical cycles. They can unlock tightly and long-held nutrients, making them more available to more host and non-host plants and altering the structure and function of the soil biotic community. Plant parasitism may also play an important role in the structure and function of ecosystems invaded by alien species. For instance, in an invaded plant community, native parasitic plants can use the invasive plants as hosts and thereby affect the growth, reproduction, biomass allocation of the invasive hosts, which may lead to changes in competitive balances between invasive host plants and non-host native plants, with repercussions for community structure and diversity. As a result, the physical, chemical and microbial properties of the soil under the invaded plant community may be altered, which may facilitate and promote the growth of non-dominant native plants, thereby changing the structure and diversity of the invaded plant community. Thus, native parasitic plants might be useful as biological control agents and they may contribute greatly to ecological restoration of invaded communities.