Agriculture using genetically modified crops is emerging as an effective measure to counteract the negative impact of abiotic stresses on crop production. Abiotic stresses mainly salt, drought, cold and heavy metals are the major cause of crop failure which restrict crops to reach their full genetic potential. Salt, drought and heavy metals exert their negative impact essentially by disrupting the ionic and osmotic equilibrium of the cell, whereas, cold causes mechanical constraint to the membrane. Plants respond to abiotic stresses through multifaceted molecular signaling pathways. Therefore, understanding of molecular signaling pathways and identification of key molecules and their specific roles is important for crop improvement. Several genes responsible for abiotic stress tolerance have been identified which code for antioxidants, enzymes that modify lipids in the cell membrane, stress-response transcription factors, proteins that maintain ion homeostasis, heat shock proteins, or enzymes that synthesize important stress-response compounds. Transgenic plants having some of these genes have been produced and found to be abiotic stress tolerant. Present chapter reviews the plant responses to abiotic stresses such as salinity, drought, cold and heavy metal stresses and tolerance mechanisms through omics approaches.