The holiday season hasn't truly started until the familiar sounds begin to take over. A few notes of "White Christmas" drift through a department store. Someone puts "It's a Wonderful Life" on the television.

That may be the magic of the season's most beloved songs, movies and customs. They are more than entertainment or decoration. They are cultural touchstones, carrying memories from one generation to the next and quietly influencing how millions of people celebrate.

"White Christmas" is the ultimate soundtrack for a holiday that, ironically, does not require snow. Irving Berlin wrote the song for the 1942 movie "Holiday Inn," and Bing Crosby introduced it on his radio show on Christmas Day in 1941. At a time when World War II was separating families and sending Americans far from home, its longing for a peaceful, familiar Christmas struck a powerful chord.

Crosby's recording became one of the best-selling singles of all time and eventually found a permanent place in American holiday culture. The song was added to the Library of Congress' National Recording Registry in 2002, recognizing its cultural and historical importance.

Its appeal is easy to understand. Whether you are looking out at a snowy neighborhood or a palm-lined street, "White Christmas" evokes a Christmas that exists somewhere in memory -- perhaps less a place than a feeling.

The same is true of the holiday movies we return to every December.

"It's a Wonderful Life," now as essential to many Christmas seasons as twinkling lights and gingerbread cookies, began with a story written by Philip Van Doren Stern. Stern reportedly conceived the idea in 1938 and eventually turned it into a short story about a despairing man who discovers how profoundly his life has affected the people around him.

The story struggled to find a publisher before becoming the basis for Frank Capra's 1946 film. The movie was not an immediate hit. In fact, it initially lost money. Years of television broadcasts, however, helped turn the film into an annual Christmas ritual.

Today, families do not simply watch George Bailey discover the value of his life. They watch it together, quote their favorite lines and argue over whether it is really Christmas Eve until the final bell rings.

"Home Alone" gave us a suburban Christmas battle involving booby traps and burglars. "A Christmas Story" gave us the leg lamp, the pink bunny suit and a warning about what happens when a child wants one particular gift more than anything else. "The Nightmare Before Christmas" proved that even Halloween and Christmas could share a holiday playlist.

And then there are the customs.

The Christmas tree. The stockings. The carols. The lights. The cookie exchange. The neighborhood drive to see the most spectacular decorations. The annual office party where someone inevitably wears a sweater that lights up.

Many of these traditions have changed dramatically over time. Yet each generation adds its own layer to the holiday, turning ordinary activities into rituals that eventually feel indispensable.

All these traditions find their way back around every year because they bring nostalgia to life. A familiar song can take us back to a childhood living room in seconds. A favorite movie can remind us of relatives who are no longer around. Even an old ornament can carry a story. Repeating these rituals gives the past a place at the holiday table.

They give us something to share. Holiday traditions create a common language. People who have never met can sing along to the same carol, laugh at the same movie scene or compare their family's Christmas-cookie recipes. The details may differ, but the basic rituals connect us.

They also give the season its signature rhythm. Part of Christmas' charm is knowing what comes next. First comes the decorating. Then the shopping, baking, parties and gatherings. Eventually, someone presses play on the annual movie, the lights go on and the familiar songs fill the house.

In a world that changes quickly, those predictable moments can be comforting.

That may be why the holidays are so full of traditions in the first place. We are not merely decorating trees, watching movies or singing songs. We are recreating memories while making new ones.