Genuine Chi (Zhen Qi) in Chinese is 真氣. It is an important and fundamental concept in Taoist meditation and internal martial arts, which all have Taoist origin. Why is it important? Because without an experiential understanding of Zhen Qi, one can't truly appreciate Taoist meditation nor internal martial arts.
Sometimes I will see a person who has been practicing an internal discipline, say tai-chi, for many years but would honestly still ask the question: what exactly is tai-chi? To give everybody the benefit of doubt, perhaps his teacher has the correct experiential feel but unable to explain and unable to teach (explain and teach are two different disciplines) it to his students, or it may also be that he thinks all this talk about Zhen Qi has no place in tai-chi!
Anyway, my view is that Zhen Qi is a most important concept in all internal disciplines. My limited search of the literature resulted only in one major mention of this concept in internal martial art (other just hinting at it, at best). And it is by a prominent YiQuan teacher Mi JingKe (祕靜克), a student of Grandmaster Wang (a Chinese book "The foundation practice of Dacheng Quan" 大成拳築基功) . This concept is commonly found in ancient Taoist meditation or internal alchemical/Neidan texts, unfortunately mythologized most of the time. And Master Mi compared her practice directly with Taoist mediation (needless to say the Master said hers is better!).
Now, what is it all about? As with other fundamental concept, its principle can easily be explained, and understood: The activation of zhen zhi is through recycling or using one's breathing energy (which is usually "wasted" every second). The point of focus is an internal point in lower abdomen or Dantian. In Taoist meditation this point is called 玄竅 (xuan qiao: the mysterious opening). Through moving this point up and down during breathing in and breathing out, a good practitioner will be able to translate, recycle or sublime the breathing energy into zhen qi which serves to connect everything inside together for different practice objectives.