Pictogram in the context of "Gender symbols"

An ideogram or ideograph (from Greek idéa 'idea' + gráphō 'to write') is a symbol that is used within a given writing system to represent an idea or concept in a given language. (Ideograms are contrasted with phonograms, which indicate sounds of speech and thus are independent of any particular language.) Some ideograms are more arbitrary than others: some are only meaningful assuming preexisting familiarity with some convention; others more directly resemble their signifieds. Ideograms that represent physical objects by visually illustrating them are called pictograms.

• Numerals and mathematical symbols are ideograms, for example ⟨1⟩ 'one', ⟨2⟩ 'two', ⟨+⟩ 'plus', and ⟨=⟩ 'equals'.
• The ampersand ⟨&⟩ is used in many languages to represent the word and, originally a stylized ligature of the Latin word et.
• Other typographical examples include ⟨§⟩ 'section', ⟨€⟩ 'euro', ⟨£⟩ 'pound sterling', and ⟨©⟩ 'copyright'.

In semiotics, a sign is anything that communicates a meaning that is not the sign itself to the interpreter of the sign. The meaning can be intentional, as when a word is uttered with a specific meaning, or unintentional, as when a symptom is taken as a sign of a particular medical condition. Signs can communicate through any of the senses, visual, auditory, tactile, olfactory, or taste.

Two major theories describe the way signs acquire the ability to transfer information. Both theories understand the defining property of the sign as a relation between a number of elements. In semiology, the tradition of semiotics developed by Ferdinand de Saussure (1857–1913), the sign relation is dyadic, consisting only of a form of the sign (the signifier) and its meaning (the signified). Saussure saw this relation as being essentially arbitrary (the principle of semiotic arbitrariness), motivated only by social convention. Saussure's theory has been particularly influential in the study of linguistic signs. The other major semiotic theory, developed by Charles Sanders Peirce (1839–1914), defines the sign as a triadic relation as "something that stands for something, to someone in some capacity". This means that a sign is a relation between the sign vehicle (the specific physical form of the sign), a sign object (the aspect of the world that the sign carries meaning about) and an interpretant (the meaning of the sign as understood by an interpreter). According to Peirce, signs can be divided by the type of relation that holds the sign relation together as either icons, indices or symbols. Icons are those signs that signify by means of similarity between sign vehicle and sign object (e.g. a portrait or map), indices are those that signify by means of a direct relation of contiguity or causality between sign vehicle and sign object (e.g. a symptom), and symbols are those that signify through a law or arbitrary social convention.

Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduced, for example the fingerposts in the United Kingdom and their wooden counterparts in Saxony.

With traffic volumes increasing since the 1930s, many countries have adopted pictorial signs or otherwise simplified and standardized their signs to overcome language barriers, and enhance traffic safety. Such pictorial signs use symbols (often silhouettes) in place of words and are usually based on international protocols. Such signs were first developed in Europe, and have been adopted by most countries to varying degrees.

A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms include throughway or thruway and parkway. Some of these may be limited-access highways, although this term can also refer to a class of highways with somewhat less isolation from other traffic.

In countries following the Vienna convention, the motorway qualification implies that walking and parking are forbidden.