What role does word of mouth play in a business?

Word of Mouth (WOM), as explained in the dictionary, is "a metaphor for the verbal praise of the masses". Traditionally, word-of-mouth refers to the face-to-face communication between non-commercial individuals about a product or company, and because it occurs among people with strong relationships such as relatives and friends, it has a great deal of influence, and therefore "word-of-mouth communication" is widely used in modern marketing promotion. With the development of communication technology and the modern network, the concept of IWOM has been put forward, which has impacted and improved the traditional concept of IWOM.