This lecture covers the principles and applications of Genome-wide Association Studies (GWAS). It explains how GWAS can identify genetic variants associated with diseases, the importance of genetic variability, and the role of imputation in inferring missing genotypes. The lecture also delves into the complexity of diseases due to genetic risk factors, the significance of SNP genotyping chips, and the process of meta-analysis for follow-up studies. Additionally, it discusses the impact of genetic variation on personalized medicine and the potential of GWAS in advancing clinical practices.