SGML(Standard Generalized Markup Language) and its application to full-text database including a table, a figure and a picture are explained. A structure of SGML based full-text database Is defined by DTD(document type definition) written in SGML, and full-text itself is described with generalized markup depending on DTD. This article explains how to represent a document structure : a hierarchical structure like a chapter, a section, or a paragraph, or non-hierarchical(referencial) structure like a note, a table, a figure or a picture. Merits of SGML, electronic publishing, a retrieval system or hypertext and SGML tools are also described.