ENFP

Primary Function: Extraverted Intuition (abbreviated Ne)
Extraverted Intuition is the function which takes in ideas from the external world and draws connections between them. To the ENFP and ENTP (Graham), types which have Ne and their first function, new and experimental are necessarily good, and old and conventional are necessarily boring. One might go so far as to say for them life is lived for novelty.
This Ne manifests most obviously in their creativity, their looking outside the box which inevitably results of their thirst for new connections. It also manifests in their irreverence; they often view tradition as necessarily bad, and a hindrance to new and better possibilities. Both of these characteristics can be seen in their ironic and absurd sense of humor, built on satire and one-upping established conventions of comedy.
There is a negative side to Ne, however. ENPs are notoriously indecisive, for one; decision is viewed as the death of possibilities. And then they are distractible and fickle like no other; when one lives to be excited, and when excitement comes from possibilities, one leaves prematurely when possibilities run dry. For the ENFP especially, this life of meeting and leaving interesting people (people as Fi territory, more on this later) frequently hurts the people when they find they were only objects of interest, and it leaves the ENFPs themselves wracked with guilt.

Auxiliary Function: Introverted Feeling (Fi)
Think of auxiliary function as an anchor for each type, or as a channel of the energy realized by the primary function. This function is where the ENFP differs from the ENTP—where the ENTP focuses his Ne on the world of preexisting ideas and theory and structures, the ENFP’s Ne is focused on Fi, the world of personal feelings and convictions.
ENFPs, as a result of this Fi, are strongly devoted to a sense of right and wrong. They live their lives in pursuit of self-fulfilling experiences: intense emotions and expressions of humanity, unrealized possibilities in individuals they consider interesting, and important potential causes which need championing. This combination of Ne and Fi is especially apparent in their relationships—ENFPs are excellent psychologists who are drawn both to the study of personality and to helping others, and most of what they say (aside from numerous jokes) is said to gauge the response of the listener and obtain a new bit of information about them. Unfortunately they will sometimes reveal a bit too much about themselves and lavish compliments and in this manner unwittingly convince others that they are more concerned about them than they actually are. The ENFP himself will often also feel guilt over this “inauthenticity.” Another negative consequence of Fi: because individuality is so important to ENFPs, they (unlike ENTPs) are likely to consider any imposition of an organization into their lives not only a threat to the realization of possibilities but also a threat to individual identity. Thus they will wage an unnecessary lifelong war against bureaucracy.

Tertiary Function: Extraverted Thinking (Te)
This function is used frequently, but only serves to aid the second function in carrying out its agenda. The user is often aware of this abuse of the function, and tries to compensate by convincing himself that he is skilled at its use independently.
For the ENTP and ENFP there is again a difference: ENTPs have Extraverted Feeling in their Tertiary Function, and their social finesse and understanding of others’ feelings and ambitions help them to promote their cause or project. ENFPs have Te, which is thinking applied to the accomplishment of goals and the meeting of criteria. Notice that this differs from the ENTP’s Introverted Thinking in auxiliary, which is thinking applied to evaluating already realized structures and ideas.
In the Tertiary Function, the Te manifests in the ENFP’s use of logic to justify or condemn behavior, and his taking personal offense to criticism of ideas which he has invested emotionally in. This both comes from a backwards logic of finding evidence with a solution already in mind. Te will also appear in hints of dogmatism, elitism, and shows of forcefulness when the ENFP is under stress.
To compensate for their weakness in this area, ENFPs try hard to prove their intellectual competence by gaining trivia knowledge, surrounding themselves with Thinking Type friends, or following cultural norms associated with intelligence.

Shadow Function: Introverted Sensing (Si)
Both ENFPs and ENTPs have Si as their last and weakest function. Si champions the value of pleasant memories and follows traditions and rituals for this sake—in this way Si is diametrically opposed to Ne. Si in the position of the Shadow Function acts as a silent anchor to all the ENFP’s and ENTP’s behaviors. It is, however, so far back down the functions line they are often not aware of it. This is evident in the signs of their lack of awareness of sensory input: very poor coordination, incompetence in picking up social etiquette, and neglecting to eat and sleep. However, its looming presence makes them nervous in new physical experiences, gives them a propensity toward nostalgia and sentimentalized memories, and draws them to engage in familiar places, customs, and (often irrational) beliefs.

Last note: EP types in general (primary functions Extraverted Sensing and Extraverted Intuition) tend to evaluate the worth of ideas or sentiments by how they are received by others. EFPs in particular are extremely concerned of what their friends think of them. ENFPs and ESFPs both will take any bit of criticism or compliment done in jest far too seriously. In the worst case, they are given to changing their own beliefs and interests to find common ground with friends.