**6. Conclusion**

Based on the technology, we discussed the general strategies of single EVs analysis including imaging, flow cytometer, nano-sensing and single EV barcoding. EVs could be classified into subsets according to their chemical composition, size, expression of specific biomarkers etc. The advancing of technologies to reveal EV heterogeneity are the pursuit of scientists from multiple disciplines.

Each EV has a unique story, the start and the end of their journey, the cargo they carried and the mission they accomplished. Revealing the heterogeneity of EVs and getting closer to the detailed facts of the abundant populations of EV will endow us the knowledge of how cells in our bodies talks to each other and what they say about our health (**Table 1**).
