The quality of agro-products is the foremost current issue for the food industry and consumers. Healthful agro-products such as fruits and vegetables, meat, grains, and dairy products are essential for human life, and reliable quality evaluation is important for product safety and consumer appeal. As a result, rapid and precise evaluation methods for the quality of agro-products are required. In this regard, optical sensing techniques such as imaging and spectroscopy are among the most promising techniques currently investigated for quality assessment purposes in agricultural fields. This chapter aims to present the basic concepts, components and principles of imaging and spectroscopy techniques in a comparative manner for agriculture application. Moreover, this chapter also elaborates upon the partiality of the optical sensing techniques by highlighting previous studies in agricultural applications. The insights in this chapter will help a novice to understand and encourage further knowledge about optical sensing techniques.