Sequestration can be divided into two categories: biological sequestration and geological sequestration (commonly known as carbon capture and storage). Biological sequestration refers to the natural process by which forests and terrestrial ecosystems serve as carbon "sinks," effectively soaking up CO2 from the atmosphere. During photosynthesis, plants take in CO2, and a portion of the carbon is stored in the plant's biomass and in soils. Land-use practices, such as forest conservation and urban forestry, can increase the amount of CO2 that is stored in the natural ecosystem.
Carbon capture and storage (CCS) employs technology to capture emissions at their source before they are released into the atmosphere. The captured carbon is then injected into underground reservoirs, or otherwise sequestered for long-term storage.
Source: US Federal Government commons.wikimedia.org