A markup language describes annotations embedded in or associated with document content. Its syntax distinguishes ordinary content from instructions identifying structure, meaning or presentation. HTML is a concrete example: a paragraph and an emphasized phrase can be represented explicitly instead of inferred from their appearance.[ref]
For example,
<p>Save <em>your work</em>.</p> identifies a paragraph containing an emphasized phrase. The angle-bracketed HTML tags mark elements; the words between them supply content. A web browser can build a Document Object Model from this source, then use CSS to choose its presentation. Changing the emphasis styling need not change which phrase is structurally emphasized.The syntax needs a way to represent its own reserved characters as content. In HTML,
< can represent a literal less-than character in text rather than starting a tag. A document explaining markup therefore needs to distinguish a displayed example from active markup that the parser interprets as document structure.[ref]A markup language is useful when documents must be transformed, searched or rendered according to their structure. It does not follow that every source annotation creates a visible box, or that a visible line break implies a particular structural element. Source syntax, the parsed document and the final rendering are related representations with different jobs.
MathML is a markup language for mathematical notation, structure and content on the web. Its elements describe expressions within a document rather than reducing a formula to a flat character string. MathML Core specifies a subset suited to web browser implementation; the cited 24June2025 document is a Candidate Recommendation Snapshot.[ref]
MathML Core by World Wide Web Consortium. Abstract; Status of This Document
Consider the typeset fraction . A presentation encoding is
<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>x</mi><mo>+</mo><mn>1</mn></mrow><mn>2</mn></mfrac></math>. The mi, mo and mn elements identify a symbolic name, an operator and numbers. The mrow groups the numerator; the two children of mfrac provide the numerator and denominator.[ref]Grouping changes the represented expression. At , the intended fraction gives , whereas . This arithmetic illustrates the meaning assigned to the structure; MathML presentation markup does not itself execute the calculation. Maintaining a structured representation helps document tools manipulate a formula and lets layout follow its mathematical grouping.
MathML Core is a browser-oriented subset of MathML with specified rules for mathematical presentation and layout. The pinned 24 June 2025 document is a Candidate Recommendation Snapshot. It defines a concrete target for implementation, rather than identifying the whole MathML language with one browser's output.[ref]
MathML Core by World Wide Web Consortium. Abstract; Status of This Document; §2.1 elements and attributes
For an original example, encode a typeset fraction surrounded by parentheses as
<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo stretchy="true">(</mo><mfrac><mi>x</mi><mn>2</mn></mfrac><mo stretchy="true">)</mo></mrow></math>. The row has three children: a left mathematical delimiter, the typeset fraction and a right mathematical delimiter. The fraction's children supply numerator and denominator 2.The parentheses are stretchy mathematical operators: their markup requests size-sensitive layout around the fraction. Core specifies operator stretching and row layout; mathematical glyph variants or mathematical glyph assemblies can supply suitable forms.[ref]
MathML Core by World Wide Web Consortium. §§3.2.4.3, 3.3.1.1 and3.3.2: operator layout, stretching and fractions
This illustrates why presenting a formula requires more than placing all its characters on one text baseline.Changing
stretchy="true" to stretchy="false" changes the layout instruction without changing the fraction's two operands. Exact dimensions also depend on the computer font and applicable layout properties. The markup supplies structure and presentation instructions; substituting a numerical value for and evaluating the quotient is a separate operation.A stretchy mathematical operator can adapt its extent to the surrounding mathematical layout. In MathML Core, an
mo element's stretchy property participates in this decision. A mathematical delimiter around a tall typeset fraction is a familiar example. Actual stretching also requires an applicable constraint and suitable computer font data.[ref]For an original example, use
<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo stretchy="true" minsize="2em" maxsize="3em">(</mo><mfrac><mi>x</mi><mn>2</mn></mfrac><mo stretchy="true" minsize="2em" maxsize="3em">)</mo></mrow></math>. The row places two mathematical delimiters around a typeset fraction with numerator and denominator 2.Suppose the positive block-axis target totals, already expressed at a common scale, are , and em. The stated size bounds adjust them to , and em, respectively. This is the target-size constraint step, not a prediction of exact rendered ink heights. The complete algorithm also handles ascent/descent and symmetry about the Math axis.[ref]
MathML Core by World Wide Web Consortium. §3.2.4.3: minsize/maxsize normalization and target-size adjustment
Suitable mathematical glyph variants or mathematical glyph assemblies can supply the extended form. Setting
stretchy="false" changes the operator's instruction without changing the fraction's two operands. Layout properties and font constructions therefore belong in a controlled comparison; enlarging every outline uniformly is not the definition of stretching. Articles by others on the same topic
A markup language is a system for annotating a document in a way that is syntactically distinguishable from the text. The annotations specify how the text should be structured and formatted, which can affect its presentation or data representation. Markup languages are widely used in web development, document processing, and data interchange. Here are some key characteristics and examples of markup languages: ### Key Characteristics: 1. **Tags**: Markup languages commonly use tags to denote the beginning and end of elements.
