This review provides an overview of microRNA (miRNA) biology, emphasizing their role in cellular communication and gene regulation. MiRNAs act as sequence-specific guides to recruit ribonucleoprotein (RNP) complexes, particularly the RNA-induced silencing complex (RISC), to target mRNAs. This process can lead to mRNA degradation or translational repression, though the effects are often more nuanced than a simple "on-off" switch. The review highlights the complexity of miRNA function, including the involvement of multiple microRNAs in target regulation and the ability of miRNAs to target both coding and noncoding RNAs. It also discusses the context-dependent nature of miRNA functions, such as the contrasting roles of miR-125b in cancer. Additionally, the review covers the regulation of miRNA expression, the role of modified miRNAs, and the impact of single nucleotide polymorphisms (SNPs) on miRNA function. Finally, it explores the interactions between miRNAs and noncoding RNAs, including lncRNAs, and the potential for miRNAs to influence lncRNA expression. The authors conclude by emphasizing the dynamic and multifaceted nature of miRNA functions, which are shaped by various cellular processes and external influences.This review provides an overview of microRNA (miRNA) biology, emphasizing their role in cellular communication and gene regulation. MiRNAs act as sequence-specific guides to recruit ribonucleoprotein (RNP) complexes, particularly the RNA-induced silencing complex (RISC), to target mRNAs. This process can lead to mRNA degradation or translational repression, though the effects are often more nuanced than a simple "on-off" switch. The review highlights the complexity of miRNA function, including the involvement of multiple microRNAs in target regulation and the ability of miRNAs to target both coding and noncoding RNAs. It also discusses the context-dependent nature of miRNA functions, such as the contrasting roles of miR-125b in cancer. Additionally, the review covers the regulation of miRNA expression, the role of modified miRNAs, and the impact of single nucleotide polymorphisms (SNPs) on miRNA function. Finally, it explores the interactions between miRNAs and noncoding RNAs, including lncRNAs, and the potential for miRNAs to influence lncRNA expression. The authors conclude by emphasizing the dynamic and multifaceted nature of miRNA functions, which are shaped by various cellular processes and external influences.