Cerium is a chemical element with the symbol Ce and atomic number 58. It belongs to the group of elements known as the lanthanides, which are found in the f-block of the periodic table. Cerium is a silvery-white metal that is relatively soft and can be easily cut with a knife. It is known for its ability to oxidize quickly when exposed to air, forming a protective layer of oxide. This element is commonly used in various applications, including catalysts in automotive exhaust systems and in the production of glass and ceramics. Cerium compounds are also utilized in polishing powders and as additives in certain types of fuel. Its unique properties make it valuable in both industrial and technological fields.