Why do we celebrate Halloween? Actually, Celtic and Roman pagans first celebrated the holiday to honor their deceased ancestors, make peace with ill fortune, and prepare for the winter. The Christian Church in Europe later appropriated the holiday to honor Saints and the deceased, and Irish and Scottish immigrants brought those traditions to America. In the mid-1900s, the holiday became more playful, resulting in the mischief, costumes, and candy-giving we're familiar with today.Trick-or-treaters are expected to spend about $1 billion more this year for candy and costumes, and that could bode well for retailers over the coming winter holidays, reports The Wall Street Journal. Sales could reach $5.8 billion this year, up from $4.75 billion a year ago, according to the National Retail Federation, and per-person spending is projected to be $66.28, way up from last year's $56.31.Since this Halloween falls on Sunday, consumers are expected to make a weekend of the holiday, decorating more elaborately and loading up on candy for children, who will be trick-or-treating all day on Sunday. Halloween is one of the Top 10 retail periods of any year and has particular importance right now because consumers are still generally apathetic about parting with their dollars unless given a special reason.Halloween candy accounts for about $2.2 billion in sales annually, and the most popular Halloween candy, according to the National Confectioners Association, is chocolate (68 percent), followed by lollipops (9 percent), gummy candy (7 percent), and gum (7 percent). Anything gory is also appealing to young boys. Halloween is the biggest time of year for candy consumption, says Harry Balzer, vice president of the NPD Group, reports USA Today, accounting for about 5 percent of all candy consumed. Parents eat one candy bar of every two the child brings home, he adds.This year, Hershey rolls out limited edition Halloween packaging for its frightfully delicious treats, reports DrugStore News. Reese's peanut butter cups are shaped like pumpkins, and Hershey's Kisses are disguised in silver, black and orange foil. Meanwhile, today only, IHOP restaurants offer kids 12 and under a free Scary Face Pancake as part of a national No Tricks - Just Treats program designed to provide kids with a safe and fun Halloween event. The "design-your-own" Scary Face Pancake includes an oversized signature buttermilk pancake with a whipped topping mouth and strawberry nose, served with two mini Oreo cookies and candy corn on the side to allow kids to create their own Halloween hotcake. Mobile devices will help parents this year with the launch of TrickorTracker, which allows them to remotely follow their children as they canvass the neighborhood for goodies. The application works through smartphones that both the child and the adult have and uses a mapping system, with the child showing up as a pumpkin on the phone's screen.Nearly 60 million adults plan to dress up this Halloween, spending more than $2 billion on costumes for themselves, their children and, yes, their pets, reports Advertising Age. Most popular choices include movie characters, comic book characters and Disney characters, according to a survey by Big Research, but there will be Snookis galore -- as well as more than a few Lady Gagas, M&Ms, Pam from "The Office" and Joan Harris from "Mad Men." Even "Mayhem" from the recent Allstate commercials was written in as a costume choice.Have a safe and happy Halloween.