The word “smart” is quite commonly associated with different types of products of IoT sensors and its contemporary technology. The frequent progress in the contemporary technology includes convention and the progressive integration of microprocessor. This gives the smart sensors application to a wide range of applications. Smart sensors when associated with agriculture are known as smart agriculture. With the help of smart sensors, technology of internet of things has helped agriculture in facilitating its efficiency, which further helps in decreasing the impact of environment on the production of the crops and deprecate the expenses. This is done by a few methods like calculating the condition of the environment, which affects the production of the crops, keeping a check on the cattle health and indicating when some problem occurs. The author discussed about sensors, their nature and evolution, generations of smarts sensors, and how they became better with the course of time in terms of smart agriculture.