Define the term 'quorum sensing'.

Quorum sensing is a process used by bacteria to regulate gene expression based on the density of their population. When the number of bacteria increases, they release signaling molecules known as autoinducers into the environment. Once these molecules reach a certain concentration, they are detected by other bacteria in the vicinity, which triggers changes in gene expression. This collective behavior allows the bacteria to coordinate activities such as biofilm formation, virulence factor production, and bioluminescence, among others. The importance of quorum sensing lies in its ability to enable bacterial communities to behave in a unified manner, enhancing their survival and adaptability in diverse environments. This mechanism underscores the sophistication of bacterial communication and organization, allowing for complex interactions within microbial populations.