The second section of Roland Barthes' "Mythologies", titled "Myth Today", is a theoretical discussion of Barthes' program for myth analysis which is demonstrated in the first section of Mythologies. What Barthes terms as "myth" is in fact the manner in which a culture signifies and grants meaning to the world around it. According to Barthes, anything can be a myth, and he follows this approach throughout the examples in Mythologies.
Barthes' concept of myth seems similar or at least draws on the concept of ideology as formulated by Marx in The German Ideology. Ideology according to Barthes' version in "Myth Today" is not entirely concealed and is subject for scrutiny through its cultural manifestations. These manifestations, mythologies according to Barthes, present themselves as being "natural" and are therefore transparent. What Barthes is after in his analysis of mythologies is to reveal the ideological nature of culture's underling myth.
At the beginning of "Myth Today" Barthes defines myth a speech. Myth is speech in that that it is part of a system of communication in which it bears meaning. By this definition Barthes expands on Levi-Strauss' perception of myth to include every symbol which conveys meaning (be it a spoken or written text, and image, a design etc. and even human actions such as sunbathing). For Barthes every cultural product had meaning, and this meaning is conditioned by ideology, i.e. myth, and therefore any cultural product can be the subject of mythological analysis and review.
According to Barthes, myth is a form of signification. However myth is different from ordinary speech and language. Barthes follows de-Saussure's discussion regarding the nature of the linguistic sign and he characterizes myth a second class of signification. What was the sign in the first order of language (for example the signifier "cigarette" and the signified of an object made of paper and tobacco) turns into a signifier in the second order (signifying lung cancer). In other words, myth for Barthes is a realm of second class signification which could be seen as a cultural association, to distinguish from denotation. Barthes, in his Rhetoric of the Image, elaborated on the difference between denotation of the sign and its connotation and its use in cultural analysis.
See also: Roland Barthes - The Death of the Author