Genome-wide association studies (GWAS) are performed to find associations between genetic variants (i.e. single-nucleotide polymorphisms) and diseases. This review describes the basic principles of GWAS. To date, GWAS have identified thousands of genetic variants associated with complex diseases and biological characteristics such as LDL cholesterol levels. GWAS can provide important insights into the underlying mechanisms of complex diseases and biological characteristics, thereby aiding the development of biomarkers and potentially pinpointing novel drug targets.