The significance of mutations in the evolutionary process is …?

Using the word “mutation” is not entirely correct. Since mutations are not useful new properties. Regressive formations are called mutations. Most of them have a bad or neutral effect on organisms. For example: cancerous tumors are the result of mutagenesis. Mutations, in the traditional sense, only hindered the evolutionary process. But useful formations directly contributed to evolution. Since the newly acquired organs, body parts, is evolution. But they appeared after thousands and millions of years.