There are many excellent descriptions of the ENTp (Intuitive Logical Extravert) out there, so I'll try to refrain from a rehash of all of those articles. But I'd like to take this opportunity to provide some of my personal observations of the type and how to know if you're in the presence of one.
- The ENTp is an enthusiastic, positive, and technically-oriented. To be blunt, if there was ever a nerd who was comfortable with being a nerd and whose nerdiness was contagious to others, that'd be an ENTp. They love talking about whatever new ideas or theories they've been researching, and they are surprisingly charming and engaging when doing so.
- The ENTp has noticeably volatile social energy levels. They jump very quickly from being animated and lively to being quietly engrossed in their own thoughts as they ponder whatever technical issue that is at the top of their mind.
- The ENTp is scatter-brained. Due to their preference for Extraverted Intuition, their thought processes tend to jump between different subjects and issues. They are often forgetful when it comes to mundane things like paying bills or administrative tasks, devoting their energy to more interesting and challenging issues.
- The ENTp likes to instruct. They are adept debaters and very knowledgeable, and they enjoy sharing what they've learned, either in the form of lecture or giving of advice.
- The ENTp is well-dressed and properly groomed. For such a technically-oriented person, they tend to invest a fair amount of time into their appearance. I believe Wikisocion aptly stated that ENTp's strive to appear "well-bred."
- The ENTp is [generally] tall and [usually] has a thin body type. Male ENTp's like to sport facial-hair (properly groomed, of course). Longer faces are common for both male and female ENTp's.