We use numerous materials in our day to day life. Most of the times, we need to group them on one or the other basis. Sorting materials is necessary for their easy management and convenient study. Your mother keeps items in the kitchen on the basis of some grouping. For example; spices may be kept on one shelf while ready-to-eat items may be kept on another shelf. Cereals may be kept in airtight containers, while vegetables may be kept in refrigerators. Scientists need to sort materials so that they can conveniently study them. Materials can be classified into two main groups, viz. metals and non-metals. They can also be classified as soluble or insoluble in water.