Chakra
"Chakra" is basically life essence or life force which exists in human bodies and animals. Without it, a shinobi can die. It can be considered "blood" and soul for a ninja. It is the molding of physical energies and spiritual energies in the body. Physical energy is the energy given off by the body cells and can be increased with more stamina and practise. Spiritual energy is derived from the consciousness of the mind and can be increased through great concentration and meditation. It is the basis for all almost all the ninja skills like Ninjutsu, Genjutsu, except Taijutsu in some special cases. It flows through the chakra circulatory system, and in it, there are 361 points aka nodes in the body known as tenkutsu. The function of the tenketsu is to regulate and control the flow of chakra. If these weren't present, then chakra would flow through some specific organ, thus there wouldn't be a balance in the chakra flow. Every ninja in the narutoverse possesses a chakra pool. Shinobis with a very high chakra pool like Naruto can perform a lot of higher ranked techniques like Multiple Shadow Clone Technique, etc. without having the fear of getting their chakra depleted at once. Senju Clan members for eg, have very high chakra reserves and a high physical energy aka high "Yang" energy, thus their naturally strong bodies and on the other hand, the Uchiha clan members have a very high spiritual energy, i.e. high "Yin" energy, thus their proficiency in genjutsu and visual prowess. It is possible to have high chakra if you possess very strong willpower. If chakra runs out completely in a shinobi, then he dies as shown when Kakashi died due to his chakra completely running out against Deva Pein. It can be divided into several types like:
Elemental Chakra
Senjutsu chakra
Bijuu Chakra
Ninjutsu
Ninjutsu means "Ninja Arts" and is something that allows the shinobi to do something that a normal human can't do, like walking on water, manipulating elements, the usage of special as well as bladed weapons, stealth, transformation, etc. The effects of ninjutsu are real. Most of the time, it heavily relies on the usage of handseals as well as chakra. Regular ninjutsu doesn't incorporate the usage of elements for it, like stealth, a basic Rasengan, etc. Elemental Ninjutsu is an advanced form of ninjutsu, which incorporates the usage of basic 5 elements, as well as advanced combinations to create stronger jutsus which have the respective properties of the 5 elements. Elemental ninjutsu is stronger to regular ninjutsu, since regular ninjutsu only uses raw chakra, whereas, elemental ninjutsu uses both Shape Manipulation and Nature Transformation. The perfect Rp example would be that, a Wind natured or a Lightning natured Rasengan would have a greater destructive force than a standard Rasengan, obviously because the elemental Rasengan contains violently rotating chakra as well as the violently rotating chakra is given the property of the respective elements.
Handseals
Handseals are hand gestures, which primarily manipulate chakra and dictate the exact amount of chakra needed for the respective specific technique. Weaving of handseals makes chakra take different "patterns". Some techniques require a large number of handseals, which is related to the complexity of performing that technique and if not weaved properly, in order, or if the user loses focus in between, then the technique is either executed in a weaker state, or it is dispersed midway, depending on the specific technique. A good example is Water Dragon Bullet Technique. It was shown that the technique required a string of 44 handseals to perform, however the Second Hokage, Tobirama could perform it with a single handseal, due to his unparalled Water mastery. It is shown in the manga that with time, a shinobi after mastering the specific technique, requires one-literally no handseals to perform it, an example being Chidori, which required some handseals when Sasuke just learnt it. In our RP, the user can perform any 2 elemental releases of his choice, depending on the elements he has placed as specialties, with one-virtually no handseals/faster handseals. Usually, handseals are performed with both the hands, but Haku, Minato, etc have demonstrated the ability to perform it with only a single hand. The 12 basic handseals are Monkey, Ram, Dog, Horse, Dragon, Boar, Rat, Snake, Ox, Hare, Bird, Tiger.
Water
Water is a more or less passive element by nature. It flows freely and takes the shape of whatever it is contained in. I call it passive as it is a yielding element which goes and flows however the external forces and nature dictate it to. For example; still water will move and ripple at the slightest touch, a river flowing straight will move around a rock and take an alternate direction instead of just going through the rock. Wind can cause water to move in different directions. This is one of the reasons why water, a yielding element, is opposite to earth, an unyielding element. That rock in the bank of the river will not move for the water, it will stay firm. If the rock were to walk through the river straight, the water would go around the rock, not the other way around. This is a rudimentary understanding, however water itself can be very powerful and forceful. A large enough mass of water may disroot the rock if strong enough. Water may be condensed to a fine area and move at great speeds to cause a powerful impact. That is where variables come in, which is what any element manipulates, the variables of the properties that can enhance an element's potential. If you want to look at things in terms of balance, Taoism and philosophies behind water and it's general movement. Water is the Yin half, not forceful, yielding and water redirects energy instead of meeting it head on. The Chinese Internal styles of martial arts talk about redirecting your opponents force back onto them which is essentially a property of water (the redirection that is). Force is not met with force rather the force is allowed to continue until redirected suddenly, often times against even harder forces that are much stronger. An example would be if somebody were to punch you. They are traveling in one direction at a certain speed. You simply move out of the way while guiding the fist further in that direction, increasing the speed. Should there be a wall behind them, they make impact with that wall and most often hurt their hand. Water can be anything from a calm and small lake to a gigantic tsunami, which causes widespread destruction. Water can be spewn from the body as a stream, fired as projectiles, or be released from the body's pores itself, as well as, you can materialize water out of thin air. Certain techniques require a source of water to insert your chakra and manipulate it to your will. Water is nearly endless and a provider of life and ultimately, divine.