This chapter provides an updated overview of acyl-lipid metabolism in Arabidopsis, covering biosynthesis, degradation, and functions of various lipid classes. It includes detailed metabolic pathways for fatty acid synthesis, plastid glycerolipid synthesis, eukaryotic phospholipid synthesis, sphingolipid synthesis, mitochondrial lipid synthesis, triacylglycerol synthesis, lipid trafficking, cuticular waxes, and suberin polyester biosynthesis. The chapter also describes methods for lipid analysis in Arabidopsis, including lipid extraction, fatty acid profiling, glycerolipid analysis, seed oil quantification, and lipidomics. A detailed summary of Arabidopsis lipid composition is provided, including 15 tables and 3 figures. The chapter is linked to an online resource (ARALIP) that provides detailed information on the metabolic pathways, enzymes, and genes involved in acyl-lipid metabolism. The chapter highlights the importance of acyl-lipids in membrane structure, energy storage, and protection against environmental stresses. It also discusses the challenges in studying lipid metabolism, including the complexity of lipid structures and the need for advanced analytical techniques. The chapter concludes with major unanswered questions in the field, including the regulation of fatty acid biosynthesis, the function of specific lipid sequences, and the molecular mechanisms of lipid transport within the plastid.This chapter provides an updated overview of acyl-lipid metabolism in Arabidopsis, covering biosynthesis, degradation, and functions of various lipid classes. It includes detailed metabolic pathways for fatty acid synthesis, plastid glycerolipid synthesis, eukaryotic phospholipid synthesis, sphingolipid synthesis, mitochondrial lipid synthesis, triacylglycerol synthesis, lipid trafficking, cuticular waxes, and suberin polyester biosynthesis. The chapter also describes methods for lipid analysis in Arabidopsis, including lipid extraction, fatty acid profiling, glycerolipid analysis, seed oil quantification, and lipidomics. A detailed summary of Arabidopsis lipid composition is provided, including 15 tables and 3 figures. The chapter is linked to an online resource (ARALIP) that provides detailed information on the metabolic pathways, enzymes, and genes involved in acyl-lipid metabolism. The chapter highlights the importance of acyl-lipids in membrane structure, energy storage, and protection against environmental stresses. It also discusses the challenges in studying lipid metabolism, including the complexity of lipid structures and the need for advanced analytical techniques. The chapter concludes with major unanswered questions in the field, including the regulation of fatty acid biosynthesis, the function of specific lipid sequences, and the molecular mechanisms of lipid transport within the plastid.