There are different Usages of the letter C.
1. the third letter of the English alphabet
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
This letter denotes the third in a set of items, categories, sizes, etc. e.g. "C batch of medicines is created after the A and B batches." It also denotes the third of three or more hypothetical people or things. e.g. "A person is sitting facing towards North, the B person is sitting facing towards South and the C person is sitting facing towards East." It also denotes the third highest class of academic mark. e.g. "Chintu gets C grade marks." It also depicts the intermediate socio-economic category for marketing purposes, including the White Collars as C1 and the Blue Collars as C2. C paper size is typically used in architectural drawings and diagrams. Besides, A4 paper fits in C5 envelope.
2. Music Chess Geology
In Music it denotes the first note of the diatonic scale of C major. And, in Chess, it denotes the third file from the left, as viewed from White's side of the board. In Geology, it denotes the lowest soil horizons, comprising parent materials.
It is used to denote 100 in the Roman Numerals as C = 100. C = Celsius or Centigrade while denoting temperature. When encircled, © becomes a Copyright symbol. the grading of lead pencils where B stands for Black. e.g. "2B, HB" Besides, B letter of English Alphabet is also used in Cuba as International Vehicle Registration. C in its lower case as c is also used in Cricket scorecards where it stands for Caught by. e.g. Sachin Tendulkar c Shane Warne 99."
C is a symbol of Element Carbon and in Physics C = Coulomb which is the SI unit of Electric Charge that equals to the quantity of Electricity conveyed in one second by a current of one Ampere. Besides, C = Capacitance which is the ability of a system to store an electric charge that can be defined as the ratio of the change of electric charge in a system to the corresponding change in its electric potential. C is also known as the name of a Computer Programming Language which was developed to implement UNIX Operating System.
the Big C which represents Cancer. e.g. "She fought well and defeated the Big C."
The most Common Noun which is used to learn this letter at the Nursery level is Cat; C for Cat.