Fine aggregate testing involves evaluating properties such as particle size distribution (gradation), specific gravity, water absorption, silt content, clay lumps, and organic impurities, as well as tests for fineness modulus, moisture content, and cleanliness. These assessments ensure the fine aggregate's suitability for concrete, mortar, and plaster applications by confirming that it provides good workability, strength, and durability without compromising the quality of the mix. Proper testing prevents issues like segregation, reduced strength, or poor bonding, thereby ensuring the finished structure's stability and longevity.