The vast kingdom of plants, particularly edibles, serving huge in the nutrition of mankind are at a risk of infestation by various pathogens resulting in a number of diseases that are known today and yet many unknown left to be discovered, as we progress further. The pathogens commonly known to infect plants belong mainly to groups of fungi, bacteria, and viruses. Viruses, as we have come to know are unique in their architecture and paradoxical with respect to the level of damage they cause despite their tiny size. History stands as testament to the menace caused by viruses in the plant world especially to the crops consumed worldwide. Thus, the initial step to deal with this problem is by devising a way, a method, or a technique to confirm its presence. This aspect is largely dealt with in detection and diagnostic studies. Unlike other pathogens, detection of plant viruses is primarily based on molecular tools. Tracing back the developments in diagnostic studies, we have come far from earliest detection methods based solely on symptomatology, indicator plants, and microscopy to many robust and accurate molecular tools like enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction with its advanced forms like real-time quantitative PCR (qPCR) droplet digital PCR (ddPCR), immununocapture PCR (IC-PCR), among others. The emerging technique of CRISPR-Cas is proving promising not only in diagnostics but management as well. This book aims to discuss the essential detection methods used in a plant virology laboratory while also deliberating about the newest developing portable techniques. This chapter gives a brief introductory lesson about Viruses discussing its architecture, taxonomy, symptomatology, transmission, and a quick preview of detection and diagnostics.