Dictionary.com defines myth this way:

A traditional or legendary story, usually concerning some being or hero or event, with or without a determinable basis of fact or a natural explanation, especially one that is concerned with deities or demigods and explains some practice, rite, or phenomenon of nature.

Myths have come a long way since the days of Greek mythology. While our modern societies still tell stories that qualify as myths, the quests and heroes have transformed to reflect the conflicts more central to the world we find ourselves in. Thus, the hero may look more like Luke Skywalker or Batman, both of whom are legendary protagonists who face supernatural forces in a battle against evil.

So why have people always engaged in these stories of supernatural strength in the face of adversity? I think that reading or watching such heroes battling evil gives the audience a sense of moral justice in the natural world we live in.

Myths take extraordinary beings and present them with extraordinary challenges. Throughout the conflict, the hero is required to reach deep, to think creatively, and to learn from others as he or she ultimately defeats evil. In the end, goodness (almost always) wins. On some level, this reinforces the idea that the world is predictable and mostly good. We all want to believe that the good guy wins in the end, that evil will not be allowed to prevail, and that we are each strong enough to overcome adversity in our own lives.

The prevalence of mythical stories fulfills this role in our lives. It allows us to believe in the legendary stories within each of us.

Myths and legends are important to us today for a number of reasons. They have value as literature, offering timeless and universal themes; they give us insight into other times and places; and they help us to see how much humankind had and has in common.

The themes of myths and legends are the same as those that are present in all great literature, just a few of which are man versus man, man versus nature, man versus the gods, man on a quest, family conflict, and coming of age. Most myths and legends include at least one of these great themes and often several. These are in the earliest "stories," the ancestors of all literature that we read today. Even aside from the beauty and creativity of these stories, which alone make them worthy of study, it enriches our study of literature today to see its earliest roots.

Every culture has its own mythology and legends and these reflect the geography of the culture, the values of the culture, and the history of the culture. Japanese creation myths, for example, reflect the fact that Japan is an island nation, and the sea and its creatures play an important part in these myths. Myths can also tell us what a culture considers ethical, significant, and central to its ideologies, giving us insight into another culture. A culture's myths, such as those of some Native Americans, tell us something about its history, the history of peoples that were hunters and gatherers, people whose governing forms did not sanction private ownership of land or disrespect the natural world. Each myth you read has something to tell you about another culture.

But in spite of the differences we see in various myths and legends, it is good to know that deep down, people are the same. We want to know how we came to be, we want to understand the natural world around us, and we yearn for some deity we can praise and blame.

Myths and legends should be part of our reading, never to be discarded as primitive, outdated, or unimportant. When I was a child, I was entranced and stimulated by the myths and legends read to me, and I, in turn, shared them with my children. I still maintain a large collection of myths from all over the world and still enjoy reading and sharing them. 

According to Dictionary.com the following applies:

Myth - a traditional or legendary story, usually concerning some being or hero or event, with our without a determinable basis in fact or a natural explanation, especially on the is concerned with deities or demigods and explaining some practice, rite or phenomenon of nature.

Every culture has had its share of myths and legends. They are used to provide a sense of identity on the part of those who tell and those are told the stories. We all have a desire to know who we are, where we came from and where we are going.

In order to address that, myths and legends tend to be used to explain things when there is no other information available. So whether it is the myth of Phaethon driving his chariot (the sun) across the sky every day to explain what that natural phenomenon is, or the glorified version of Christopher Columbus where the ugly parts are glossed over and only the desired parts of the story survive--myth evokes feeling, provides context and completes "the story" even for readers today.