Kress and van Leeuwen defined multimodality as“the use of several semiotic modes in the design of a semiotic product or event”（Kress and van Leeuwen，2001：20）.Therefore，multimodality approaches representation，communication and interaction as something more than language.The starting point for multimodality is to extend the social interpretation of language and its meanings to the whole range of representational and communicational modes or semiotic resources for making meaning that are employed in a culture—such as image，writing，gesture，gaze and speech（Jewitt，2009：1）.

Multimodality is a relatively new approach to research on discourses.It was not until the mid to late 1980s that Hallidayan discourse analysis began to take serious note of meaning making other than language（Iedema，2003）.However，its development is impressively fast.There has been a significant body of work on multimodality that address theoretical questions and that apply the multimodal principles in the analysis of a range of discourse genres in print media，dynamic and static electronic media and threedimensional objects in space.The theoretical approach informing these research efforts is Michael Halliday's systemic functional theory of language and social semiotics which are extended to other semiotic resources（O'Halloran，2004：1;Jewitt，2009：29）.

Since the scope of semiotic modes involved in the field of multimodality is very broad，this section will focus on those works that concern the relations between language and image.the key tenets of the multimodal discourse analysis will be reviewed in Subsection 2.2.1.Sub-section 2.2.2 will focus the theoretical research on inter-semiotic relations.Sub-section 2.2.3 will concern the studies aiming at building frameworks of visual-verbal relations on the basis of sample analysis.In Sub-section 2.2.4 the studies which apply the multimodal discourse analysis approach to specific genres will be reviewed，with special attention to the genres that are most relevant to the English learning advertisements under discussion in this book：advertising genres and educational genres.Sub-section 2.2.5 will be a brief introduction of the current state of the multimodality as a research area in China.