The Pharisees were a Jewish religious sect that was active during the ministry of Jesus and the beginnings of the early church but disappeared after the destruction of the Jerusalem temple in 70 AD. While speculations about the Pharisees abound, such speculations are often based on very little hard evidence. In reality, we do not know when they arose, why they arose, what their name means, how many of them there were, what exactly they believed, or what sort of influence they may have had. Of course this has not stopped scholars from spinning theories, plausible and implausible, about all of the above!
It is generally accepted that the primary concerns of the Pharisees were the maintenance of a very strict table fellowship (e.g., not eating with anyone they would consider unclean) and with an “intensification” of the Torah by means of increasingly elaborate oral traditions. Though their numbers were likely small, and their direct political power minuscule, their reputation for piety gave them significant influence over the common people. The inevitable abuse of that influence by at least some of the Pharisees led to the hypocrisy and covetousness so often condemned by Jesus.