The Endoplasmic Reticulum (ER) is a network of membranes found in eukaryotic cells. It plays a crucial role in the synthesis and transport of proteins and lipids. There are two types of ER: rough and smooth. The rough ER is studded with ribosomes, which are responsible for making proteins, while the smooth ER is involved in lipid production and detoxification processes. The ER is essential for maintaining cellular health and function. It helps in folding proteins correctly and ensuring they reach their proper destinations within the cell. Any issues with the ER can lead to diseases, highlighting its importance in cellular biology and overall organism health.