In HTML, div and span tags are elements used to define parts of a document, so that they are identifiable when a unique classification is necessary. Where other HTML elements such as p (paragraph), em (emphasis), and so on, accurately represent the semantics of the content, the additional use of span and div tags leads to better accessibility for readers and easier maintainability for authors. Where no existing HTML element is applicable, span and div can valuably represent parts of a document so that HTML attributes such as class, id, lang, or dir can be applied.
span represents an inline portion of a document, for example words within a sentence. div represents a block-level portion of a document such as a few paragraphs, or an image with its caption. div stands for division. The elements allow semantic attributes (e.g. lang="en-US"), CSS styling (e.g., color and typography), or client-side scripting (e.g., animation, hiding, and augmentation) to be applied.
div defines a 'division' of the document, a block-level item that is more distinct from elements above and below it than a span of inline material.
Examples
For example, to make a certain part of text inside a paragraph red, span can be used as follows:
History
The span element was introduced to HTML in the internationalization working group's second draft html-i18n in 1995. However, it was not until HTML 4.01 that it became part of the HTML language, appearing in the HTML 4 W3C Working Draft in 1997.
In 1995, span was introduced to mark up any inline span of text, because 'a generic container is needed to carry the LANG and BIDI attributes in cases where no other element is appropriate.' It still serves that general purpose, although a much richer range of semantic elements have been defined since then, and there are also many more attributes that may need to be applied.
Differences and default behaviour
There are multiple differences between div and span. The most notable difference is how the elements are displayed. In standard HTML, a div is a block-level element whereas a span is an inline element. The div block visually isolates a section of a document on the page, and may contain other block-level components. The span element contains a piece of information inline with the surrounding content, and may only contain other inline-level components. In practice, the default display of the elements can be changed by the use of Cascading Style Sheets (CSS), although the permitted contents of each element may not be changed. For example, regardless of CSS, a span element may not contain block-level children.
Practical usage
span and div elements are used purely to imply a logical grouping of enclosed elements.
There are three main reasons to use span and div tags with class or id attributes:
Styling with CSS
It is common for and elements to carry class or id attributes in conjunction with CSS to apply layout, typographic, color, and other presentation attributes to parts of the content. CSS does not just apply to visual styling: when spoken out loud by a voice browser, CSS styling can affect speech-rate, stress, richness and even position within a stereophonic image.
For these reasons, and in support of a more semantic web, attributes attached to elements within HTML should describe their semantic purpose, rather than merely their intended display properties in one particular medium. For example, the HTML in is semantically weak, whereas uses an em element to signify emphasis (appearing as text in italics), and introduces a more appropriate class name. By the correct use of CSS, such 'warnings' may be rendered in a red, bold font on a screen, but when printed out they may be omitted, as by then it is too late to do anything about them. Perhaps when spoken they should be given extra stress, and a small reduction in speech-rate. The second example is semantically richer markup, rather than merely presentational.
Semantic clarity
This kind of grouping and labelling of parts of the page content might be introduced purely to make the page more semantically meaningful in general terms. It is impossible to say how the World Wide Web will develop in years and decades to come. Web pages designed today may still be in use when information systems that we cannot yet imagine are trawling, processing, and classifying the web. Even today's search engines such as Google and others use proprietary information processing algorithms of considerable complexity.