Storage of C O₂ in saline aquifers is a viable option for reducing the amount of CO₂ released to the atmosphere. This paper provides an overall review of CO₂ sequestration in saline aquifers. First, the principles of CO₂ sequestration are presented, including CO₂ phase behavior, CO₂-water-rock interaction, and CO₂ trapping mechanisms. Then storage capacity and CO₂ injectivity are discussed as the main determinants of the storage potential of saline aquifers. Next, a site section process is addressed considering basin characteristics, reservoir characteristics, and economic and social concerns. Three main procedures are then presented to investigate the suitability of a site for CO₂ sequestration, including site screening, detailed site characterization, and pilot field-scale test. The methods for these procedures are also presented, such as traditional site characterization methods, laboratory experiments, and numerical simulation. Finally, some operational aspects of sequestration are discussed, including well type, injection rate, CO₂ purity, and injection strategy.