<b>A Study on Face Expression Observation Systems</b> Human expressions can convey a great deal of information. We cannot learn every language in the world, but we can decipher the majority of human expressions. The state of a user s conduct in various settings and scenarios can be inferred from their facial expressions. Through various human computer interface and programming approaches, facial expression can be digitized. Face detection, feature extraction, and kind of expression determination are all parts of the facial expression perception process. Verbal and non verbal forms of communication are both possible. Through their emotions, people can communicate nonverbally We ve given a broad summary of the various facial expression perception processes in the literature in this article. Face Expressions, Neural Nets, Knowledge, Statistics 237-243 Issue-5 Volume-6 Jyoti | Neeraj Chawaria | Ekta