The Indian standard classification of soil is based on the M.I.T (Massachusetts Institute of Technology) system.

Explanation:
The M.I.T system of soil classification was developed by the Massachusetts Institute of Technology in the United States. It is widely used internationally and has been adopted by various countries including India. The Indian standard classification of soil is based on this system.

The M.I.T system classifies soils based on their engineering properties and behavior. It takes into account various factors such as grain size, plasticity, and compressibility. The classification is primarily based on the results of laboratory tests conducted on soil samples.

The Indian standard classification of soil divides soils into several broad groups based on their properties. These groups are further divided into subgroups and further into fine-grained and coarse-grained soils. The classification system is hierarchical and provides a systematic way to categorize soils based on their characteristics.

The Indian standard classification of soil is important in civil engineering as it helps in understanding the behavior of soils and determining their suitability for various construction activities. Different types of soils have different engineering properties and behavior, and it is essential to classify them accurately to make informed decisions regarding their use in construction projects.

In conclusion, the Indian standard classification of soil is based on the M.I.T system, which provides a systematic way to categorize soils based on their engineering properties and behavior. This classification system is widely used internationally and is important in civil engineering for assessing the suitability of soils for construction activities.