There are two main types of cohesion: grammatical cohesion which is based on structural content, and lexical cohesion which is based on lexical content and background knowledge. A cohesive text is created in many different ways. In Cohesion in English, M.A.K. Halliday and Ruqaiya Hasan identify five general categories of cohesive devices that create coherence in texts:
REFERENCE
ELLIPSIS
SUBSTITUTION
LEXICAL COHESION
CONJUNCTION