Mail

Mail is a method for transmitting in order and solid objects, wherein written documents, typically enclosed in envelopes, and also small packages, are delivered to destinations around the world. Anything sent through the postal system is called mail or post.

In opinion, a postal service can be private or public. Governments often place restrictions on private postal freedom systems. Since the mid 19th century national postal systems have generally been established as government monopolies with a fee on the article prepaid. confirmation of payment is often in the form of cement postage stamps, but postage meters are also used for bulk mailing.

Postal systems often have functions other than sending letters. In some countries, the postal system also has some influence over telephone and telegraph systems. In others, postal systems allow for savings accounts and handling applications for passports.

Earth

Earth is the third planet from the Sun and is the largest of the global planets in the Solar System, in both diameter and mass. It is also referred to as the Earth, Planet Earth, and the World, and in some contexts, Gaia and Terra.

Home to millions of species, including humans, Earth is the only place in the cosmos where life is known to exist. Scientific substantiation indicates that the planet formed 4.54 billion years ago, and life appeared on its shell within a billion years. Since then, Earth's biosphere has significantly altered the tone and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful emission, permitting life on land.

Earth's outer surface is divided into several firm segments, or tectonic plates, that gradually journey across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the leftovers consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inside core.

Earth interacts with other objects in outer space, including the Sun and the Moon. At present, Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° away from the upright to its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt and gradually slows the planet's rotation. A cometary barrage during the early history of the planet played a role in the formation of the oceans. Later, asteroid impacts caused significant changes to the surface atmosphere. Long term periodic changes in the Earth's orbit, caused by the gravitational influence of other planets, are believed to have given rise to the ice ages that have intermittently covered momentous portions of Earth's surface in glacial sheets.