**Abstract**

*Staphylococcus aureus* (*S. aureus*) has been a substantial economic problem due to its antibiotic resistance, persistence inside host and recurrence of disease. It escapes from immunity because of its intra-cellular growth. Moreover, it forms biofilm on both living and in-animate surfaces that leads to recurrent infections and growth in food industry, respectively. Further, *S. aureus* undergoes the vertical and horizontal evolution that has genetically diversified the bacterial population. All the factors such as point mutations, plasmids, phages etc. have played their roles in diversifying this bacterium. Many bacterial physiological characteristics have been affected by genetic diversity. Biofilm forming ability is also considered as a variable characteristic of *S. aureus* that can help the bacteria to survive in different environments with different levels of biofilm production. In adapting the environment, *S. aureus* also forms different types of biofilm for its better survival. How genetic diversity is playing its role in this division of *S. aureus* is yet to be revealed. This chapter focuses on the factors related to genetic diversity and biofilm formation of *S. aureus*.

**Keywords:** Genetic diversity, Non-synonymous mutations, ica-operon, biofilm production, agr-operon
