ಸಂಖ್ಯೆ ಎನ್ನುವುದು ಎಣಿಕೆ ಮತ್ತು ಅಳತೆಯಲ್ಲಿ ಉಪಯೋಗಿಸುವ ಒಂದು ಅಮೂರ್ತ ಕಲ್ಪನೆ. ಗಣಿತಶಾಸ್ತ್ರದಲ್ಲಿ, ಸಂಖ್ಯೆಯ ಪರಿಕಲ್ಪನೆಯನ್ನು ವಿಸ್ತರಿಸಿ ಸ್ವಾಭಾವಿಕ ಸಂಖ್ಯೆಗಳು, ಸೊನ್ನೆ, ಧ್ರುವ ಸಂಖ್ಯೆಗಳು, ಋಣ ಸಂಖ್ಯೆಗಳು ಇನ್ನೂ ಮುಂತಾದ ಹೊಸ ರೀತಿಯ ಸಂಖ್ಯೆಗಳನ್ನೂ ಸೇರಿಸಿಕೊಳ್ಳಲಾಗಿದೆ.

A number is a mathematical object used to count, measure, and label. The most basic examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can be represented by symbols, called numerals; for example, "5" is a numeral that represents the number five. As only a relatively small number of symbols can be memorized, basic numerals are commonly organized in a numeral system, which is an organized way to represent any number. The most common numeral system is the Hindu–Arabic numeral system, which allows for the representation of any non-negative integer using a combination of ten fundamental numeric symbols, called digits. In addition to their use in counting and measuring, numerals are often used for labels, for ordering, and for codes. In common usage, a numeral is not clearly distinguished from the number that it represents.