Microarray technology is a high-throughput technique that enables the simultaneous analysis of gene expression across thousands of genes also known as DNA chips or gene chips. This method relies on microscopic slides containing predefined DNA sequences. Along with next-generation sequencing (NGS), the DNA chip method has profoundly impacted various aspects of biological research. Researchers can assess gene expression by hybridizing fluorescently labeled complementary DNA (cDNA) samples to these arrays under different environmental conditions. In this process, mRNA is extracted from both a treated (or diseased) sample and an untreated (or healthy) sample, converted into cDNA, and labeled with different fluorescent dyes. Microarray technology plays a crucial role in single nucleotide polymorphism (SNP) detection, drug discovery, disease diagnostics, and personalized medicine. Despite its advantages, microarrays also have certain limitations, such as background noise, cross-hybridization, and an inability to detect novel transcripts. With ongoing advancements in bioinformatics, microarrays continue to evolve, integrating with other genomic technologies to enhance precision and reliability. This chapter provides a comprehensive overview of microarray technology, detailing its evolution, current applications, and future prospects.