Essential to even the most basic jutsu, chakra is mixture of the energy present in every cell of the body and the spiritual energy gained from exercise and experience. Once mixed, it can be channeled through the chakra circulatory system, which is to chakra as the regular circulatory system is to blood, to any of the 361 chakra points on the body. Through various methods, the most common of which is handseals, the chakra can then be manipulated to create an effect that would not be possible otherwise, such as walking on water.
Depending on the ratio in which physical and spiritual energy is mixed, different types of chakra can be formed. Elemental chakra is the most common product of this, and is used to perform elemental jutsu. The five elemental natures are earth, fire, lightning, water, and wind. Most ninja have a natural affinity to one type of chakra, but have the capacity to create elemental chakra apart from their own affinity. Each element is both stronger and weaker than another. The order is fire, wind, lightning, earth, and water, with each being weaker than the previous and stronger than the next. Water loops back into fire. Additionally, elemental techniques can be countered by techniques of the same element, provided the technique being countered is of equal or lesser power.
Certain kekkei genkai can also create unique elements, such as wood and ice, through a mixture of the basic elements, which normal ninja are incapable of doing. While some ninja are capable of producing varied types of chakra, they can't do so simultaneously. Yamato also mentions light and dark chakra, but doesn't elaborate on what they're used for. An example of dark chakra would be the Nara clan, as seen when Shikamaru uses chakra knives to absorb his chakra, and give it the same abilities as his Shadow Imitation Technique. Examples of light chakra haven't been given yet.
