decades, "free delivery" was a popular slogan for almost all pizza stores. In Australia, a portion of the delivery charge is given to the driver as the store is required to reimburse the driver for the use of a personal vehicle. Domino's Pizza is credited with popularizing free pizza delivery in the United States. Pizza Hut began experimenting in 1999 with a 50-cent delivery charge in ten stores in the Dallas-Fort Worth area. By mid-2001 it was implemented in 95% of its 1,749 company-owned restaurants in the U.S., and in a smaller number of its 5,250 franchisee-owned restaurants. By 2002, a small percentage of stores owned or franchised by U.S. pizza companies Domino's and Papa John's were also charging delivery fees of 50 cents to $1.50, and some of Little Caesar's franchisees charged delivery fees. In 2005, Papa John's implemented delivery charges in the majority of its company-owned stores. In some countries, it is common to give the pizza deliverer an optional tip upon paying for the order. In Canada and the United States, tipping for pizza delivery is customary. Opinions on appropriate amounts vary widely. Employees are legally obligated to report tips to their employer for income tax purposes, while independent contractors, who may charge a per-delivery fee to a restaurant, are legally obligated to report tips to the Internal Revenue Service. Delivery technology Delivery bag Bags used to keep pizza hot while being transported are commonly referred to as hotbags or hot bags. Hotbags are thermal bags, typically made of vinyl, nylon, or Cordura, that passively retain heat. Material choice affects cost, durability, and condensation. Heated bags supply added heat through insertion of externally heated disks, electrical heating elements, or pellets heated by induction from electrically generated magnetic waves. Innovations in delivery bag designs have allowed without the usage of a fixed box for bike delivery, such as a hard frame, back straps, and waterproofing. These systems proved to be cheaper, more efficient and faster to use. Pizza box Modern pizza boxes are made of corrugated fiberboard. Corrugated board has a number of advantages for pizza delivery: it is cheap, recyclable, and disposable, it is stiff yet light, it is absorbent thus keeping oil and juice from leaking, and the channels of air in the cardboard have excellent insulation properties. The history of the pizza box began in Naples during the 1800s where bakers put pizzas into metal