Christmas, also referred to as Christmas Day, is an annual holiday celebrated on December 25 or January 7 that commemorates the birth of Jesus of Nazareth. The day marks the beginning of the larger season of Christmastide, which lasts twelve days. The nativity of Jesus, which is the basis for the anno Domini system of dating, is thought to have occurred between 7 and 2 BC. December 25 is not thought to be Jesus' actual date of birth, and the date may have been chosen to correspond with either a Roman festival, or with the winter solstice.
Modern customs of the holiday include gift-giving, Church celebrations, and the display of various decorations—including the Christmas tree, lights, mistletoe, nativity scenes, and holly. Santa claus (also referred to as Father Christmas, although the two figures have different origins) is a popular mythological figure often associated with bringing gifts at Christmas for children. Santa is generally believed to be the result of a syncretization between Saint Nicholas and elements from pagan Nordic and Christian mythology, and his modern appearance is believed to have originated in 19th century media.
Christmas is celebrated throughout the Christian population, but is also celebrated by many non-Christians as a secular, cultural festival. Because gift-giving and several other aspects of the holiday involve heightened economic activity among both Christians and non-Christians, Christmas has become a major event for many retailers.

A Christmas decoration is any of several types of decorations used at Christmastime. The traditional colors of Christmas are pine green (evergreen), snow white, and heart red. Blue and white are often used to represent winter, or sometimes Hanukkah, which occurs around the same time. Gold and silver are also very common, as are just about any other metallic color. Typical icons of the holiday include Santa claus, Jesus, the star of Bethlehem, and the Christian cross. Typical winter icons include snowflakes, snowmen, icicles, and even penguins and polar bear.
In many countries there are many different types of decorations used depending on the traditions and available resources.
The Christmas tree is often explained as a Christianization of pagan tradition and ritual surrounding the winter solstice, which included the use of evergreen boughs, and an adaptation of pagan tree worship. The English language phrase "Christmas tree" is first recorded in 1835and represents an importation from the German language. The modern Christmas tree tradition is believed to have begun in Germany in the 18th century though many argue that Martin Luther began the tradition in the 16th century. from Germany the custom was introduced to England, first via Queen Charlotte, wife of George III, and then more successfully by Prince Albert during the reign of Queen Victoria. Around the same time, German immigrants introduced the custom into the United States. Christmas trees may be decorated with lights and ornaments

Typical examples of an inflatable include the inflatable boat, the balloon, the airship, furniture, kites, and numerous air-filled swimming pool toys. Air beams as structural elements are finding increasing applications. Balloons are inflatables.
Smaller-scale inflatables (such as pool toys) generally consist of one or more "air chambers", which are hollow enclosures bound by a soft and flexible airtight material (such as vinyl), which a gas can enter into or leave from through valves (usually one on each air chamber). The design dependence upon an enclosed pocket of gas leads to a need for a very durable surface material and/or ease of repair of tears and holes on the material, since a puncture or tear will result in the escape of the gas inside (a leak) and the deflation of the inflatable, which depends on the gas's pressure to hold its form. Detectable leaks can be caused by holes (from punctures or tears) on the material, the separating of seams, the separating of valve parts, or an improperly shut or improperly closing valve. Even if an inflatable possesses no macroscopic leaks, the gas inside will usually diffuse out of the inflatable, albeit at a much slower rate, until equilibrium is reached with the pressure outside the inflatable.
Many inflatables are made of material that does not stretch upon inflation; a notable exception of this is the balloon, whose rubber stretches greatly when inflated.
The airship is usually inflated with helium as it is lighter than air and does not burn unlike hydrogen airships such as the Hindenburg.
Inflatables are also used for the construction of specific sports pitches, military quick-assembly tents, camping tent air beams, and noise makers. Inflatable aircraft including the Goodyear Inflatoplane have been used. Inflation by dynamic ram-air is providing wings for hang gliding and paragliding.
Inflatables came very much into the public eye as architectural and domestic object when synthetic materials became commonplace. Iconic structures like the US Pavilion at the 1970 Osaka Expo by Davis and Brody and Victor Lundy's travelling pavilion for the Atomic Energy Commission popularized the idea that inflatables can be a way to build large structures with very extended interior spans without pillars. These great hopes for inflatable structures would later be dashed by the many practical difficulties faced by inflatable buildings, such as climatization, safety, sensitivity to wind and fire proofing that, currently, restrict their use to very specific circumstances.

Large scale low-pressure inflatables are often seen at festivals as decorations or inflatable games. These are made out of rip stop nylon and have a constant flow of air from a blower inflating them.
In some cases, an inflatable roof is added to an otherwise traditional structure: the biggest example in the world is currently the BC Place Stadium in Vancouver, British Columbia.
Inflatable structures are structures made of a flexible outer membrane or fabric that is filled with air or helium inside. These fluids have the purpose of giving the shape and strength of the structure regardless of external atmospheric or use conditions. The structural behavior of the inflatable structure depends on the strength of the external membrane. The final use, shape and the size of the structure depend on the specific design and requirements that their end users determine.
Nowadays, inflatable structures and inflatable buildings are used in many ways. Membrane roofs and covers, inflatable castles and games, sails, airships, inflatable furniture, airspace structures, Inflatable boats, inflatable escape slides, security mattresses, inflatable swimming pools, inflatable coverings, inflatable pavilions for events, inflatable buildings and pavilions, air bags and many other applications. The great technology and applicability of inflatable structures is the result of the increasing use and experience in different industries and sectors.
 
The name given to such structures varies. In playground terms: In the United States, East Coasters refer to them as a "moon bounce" while West Coasters stick to the generic name of "inflatable playground". They have been marketed with such names as Moon Bounce, Moonwalk, Bounce house, Spacewalk, in the US, bouncy castle or inflatable castle in Ireland, the UK and parts of Australia, and as jumping castles in Arizona, Australia, New Zealand, Canada and South Africa. The term "moonwalk" has evolved as the generic term for enclosed inflatable trampolines in the US.
Inflatable structures are rented for functions, school and church festivals and village fetes. Although they are aimed at children, adult castles can be hired in the UK. Because of liability concerns, moonwalks are rarely rented to adults in the US.
The growth in popularity of moonwalks has led to an inflatable amusement industry which includes inflatable slides, obstacle courses, games, and more. Inflatables are ideal for portable amusements because they are easy to transport and store.