Data is a general term for a set of observations and measurements collected during any type of systematic investigation.

Primary data is data collected by the user. Secondary data is data collected by others. Sources of secondary data include, web-based data sets, the media, books, scientific papers, etc.

Univariate data is data relating to a single variable, for example, hair colour or the number of errors in a test.

A data display is a visual format for organising and summarising data.

Examples include, box plots, column graphs, frequency tables and stem plots.​

A decimal is a numeral in the decimal number system.

For example, the decimal expansion of  is 6.75. The integer part is 6 and the fractional part is 0.75

A decimal is terminating if the fractional part has only finitely many decimal digits. It is non-terminating if it has infinitely digits.

For example, 6.75 is a terminating decimal, whereas 0.3161616 ..., where the pattern 16 repeats indefinitely, is non-terminating.

Non-terminating decimals may be recurring, that is, contain a pattern of digits that repeats indefinitely after a certain number of places.

For example, 0.3161616... is a recurring decimal, whereas .101001000100001... where the number of 0s between the 1s increases indefinitely, is not recurring.

It is common practice to indicate the repeating part of a recurring decimal by using dots or lines as superscripts.

For example, 0.3161616... could be written as  or 

The decimal number system is the base 10, place-value system most commonly used for representing real numbers. In this system positive numbers are expressed as sequences of Arabic numerals 0 to 9, in which each successive digit to the left or right of the decimal point indicates a multiple of successive powers (respectively positive or negative) of 10.

For example, the number represented by the decimal 12.345 is the sum 

audio, visual or multimodal texts produced through digital or electronic technology, which may be interactive and include animations and/or hyperlinks. Examples of digital texts include DVDs, websites, e-literature