A post office is a public facility and a retailer that provides mail services, such as accepting letters and parcels, providing post office boxes, and selling postage stamps, packaging, and stationery. Post offices may offer additional services, which vary by country. These include providing and accepting government forms (such as passport applications), and processing government services and fees (such as road tax, postal savings, or bank fees).  The chief administrator of a post office is called a postmaster.
Before the advent of postal codes and the post office, postal systems would route items to a specific post office for receipt or delivery. During the 19th century in the United States, this often led to smaller communities being renamed after their post offices, particularly after the Post Office Department began to require that post office names not be duplicated within a state. 
The term "post-office"  has been in use since the 1650s,  shortly after the legalisation of private mail services in England in 1635.  In early modern England, post riders—mounted couriers—were placed, or "posted",  every few hours along post roads at posting houses (also known as post houses) between major cities, or "post towns". These stables or inns permitted important correspondence to travel without delay. In early America, post offices were also known as stations. This term, as well as the term "post house", fell from use as horse and coach services were replaced by railways, aircraft, and automobiles.
Today, the term "post office" usually refers to government postal facilities providing customer service. "General Post Office" is sometimes used for the national headquarters of a postal service, even if the building does not provide customer service. A postal facility that is used exclusively for processing mail is instead known as a sorting office or delivery office, which may have a large central area known as a sorting or postal hall. Integrated facilities combining mail processing with railway stations or airports are known as mail exchanges.
In India, post offices are found in almost every village having panchayat (a "village council"), towns, cities, and throughout the geographical area of India. India's postal system changed its name to India Post after the advent of private courier companies in the 1990s. It is run by the Indian government's Department of Posts.  India Post accepts and delivers inland letters, postcards, parcels, postal stamps, and money orders (money transfers). Few post offices in India offer speed post (fast delivery) and payments or bank savings services. It is also uncommon for Indian post offices to sell insurance policies or accept payment for electricity, landline telephone, or gas bills. Until the 1990s, post offices would collect fees for radio licenses, recruitment for government jobs, and the operation of public call telephone (PCO) booths. Postmen would deliver letters, money orders, and parcels to places that are within the assigned area of a particular post office but there are no post offices in the location. Each Indian post office is assigned a unique six-digit code called the Postal Index Number, or PIN. Each post office is identified by its PIN.
Private courier and delivery services often have offices as well, although these are usually not called "post offices", except in the case of Germany, which has fully privatised its national postal system.[ citation needed ]
As abbreviation PO is used, together with GPO for General Post Office and LPO for Licensed Post Office.
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There is evidence of corps of royal couriers disseminating the decrees of Egyptian pharaohs as early as 2400 BCE, and it is possible that the service greatly precedes that date. Similarly, there may be ancient organised systems of post houses providing mounted courier service, although sources vary as to precisely who initiated the practice. 
In the Persian Empire, a Chapar Khaneh system existed along the Royal Road. Similar postage systems were established in India and China by the Mauryan and Han dynasties in the 2nd century BCE.
The Roman historian Suetonius credited Augustus with regularising the Roman transportation and courier network, the Cursus Publicus . Local officials were obliged to provide couriers who would be responsible for their message's entire course. Locally maintained post houses (Latin : stationes ) privately owned rest houses (Latin : mansiones ) and were obliged or honored to care for couriers along their way. The Roman emperor Diocletian later established two parallel systems: one providing fresh horses or mules for urgent correspondence and the other providing sturdy oxen for bulk shipments. The Byzantine historian Procopius, though not unbiased, records the Cursus Publicus system remained largely intact until it was dismantled in the Byzantine empire by the emperor Justinian in the 6th century.
The Princely House of Thurn and Taxis family initiated regular mail service from Brussels in the 16th century, directing the Imperial Post of the Holy Roman Empire. The British Postal Museum claims that the oldest functioning post office in the world is on High Street in Sanquhar, Scotland. The post office has functioned continuously since 1712, during which horses and stagecoaches were used to carry mail.
In parts of Europe, special postal censorship offices existed[ when? ] to intercept and censor mail. In France, such offices were known as cabinets noirs.
In many jurisdictions, mailboxes and post office boxes have long been in widespread use for drop-off and pickup (respectively) of mail and small packages outside post offices or when offices are closed. Germany's national postage system Deutsche Post introduced the Pack-Station for package delivery, including both drop-off and pickup, in 2001. In the 2000s, the United States Postal Service began to install Automated Postal Centers (APCs) in many locations in both post offices, for when they are closed or busy, and retail locations.  APCs can print postage and accept mail and small packages.
The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the U.S., including its insular areas and associated states. It is one of the few government agencies explicitly authorized by the U.S. Constitution. The USPS, as of 2021, has 516,636 career employees and 136,531 non-career employees.
The mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal systems have generally been established as a government monopoly, with a fee on the article prepaid. Proof of payment is usually in the form of an adhesive postage stamp, but a postage meter is also used for bulk mailing. With the advent of email, the retronym "snail mail" was coined.
The United States Post Office Department was the predecessor of the United States Postal Service, in the form of a Cabinet department, officially from 1872 to 1971. It was headed by the postmaster general.
Package delivery or parcel delivery is the delivery of shipping containers, parcels, or high value mail as single shipments. The service is provided by most postal systems, express mail, private courier companies, and less than truckload shipping carriers.
This is a partial timeline of significant events in postal history, including dates and events relating to postage stamps.
International Distributions Services plc, trading as Royal Mail, is a British multinational postal service and courier company, originally established in 1516 as a government department. The company's subsidiary Royal Mail Group Limited operates the brands Royal Mail and Parcelforce Worldwide (parcels). GLS Group, an international logistics company, is a wholly owned subsidiary of Royal Mail Group. The group used the name Consignia for a brief period in the early 2000s and Royal Mail until October 2022.
This a survey of the postage stamps and postal history of the Russian Empire, the Soviet Union and the modern Russian Federation.
Registered mail is a mail service offered by postal services in many countries which allows the sender proof of mailing via a mailing receipt and, upon request, electronic verification that an article was delivered or that a delivery attempt was made. Depending on the country, additional services may also be available, such as:
Australia Post, formally the Australian Postal Corporation, is the government business enterprise that provides postal services in Australia. The head office of Australia Post is located in Bourke Street, Melbourne, which also serves as a post office.
Poste restante, also known as general delivery in North American English, is a service where the post office holds the mail until the recipient calls for it. It is a common destination for mail for people who are visiting a particular location and have no need, or no way, of having mail delivered directly to their place of residence at that time.
India Post is a government-operated postal system in India, part of the Department of Post under the Ministry of Communications. Generally known as the Post Office, it is the most widely distributed postal system in the world. Warren Hastings had taken initiative under East India Company to start the Postal Service in the country in 1766. It was initially established under the name "Company Mail". It was later modified into a service under the Crown in 1854 by Lord Dalhousie. Dalhousie introduced uniform postage rates and helped to pass the India Post Office Act 1854 which significantly improved upon 1837 Post Office act which had introduced regular post offices in India. It created the position Director General of Post for the whole country.
Singapore Post Limited, commonly abbreviated as SingPost, is an associate company of Singtel and Singapore's designated Public Postal Licensee which provides domestic and international postal services.
Military mail, as opposed to civilian mail, refers to the postal services provided by armed forces that allow serving members to send and receive mail. Military mail systems are often subsidized to ensure that military mail does not cost the sender any more than normal domestic mail. In some cases, military personnel in a combat zone may post letters and packages to their home country free of charge. Modern military mail services are provided by most armed forces around the world. In some nations, individual service branches may run their own military mail program.
Russian Post is an Aktsionernoye Obschestvo which is the national postal operator of Russia. The company is responsible for the delivery of mail in Russia, and the issuing of postage stamps. Russian Post employs about 390,000 people and has over 42,000 post offices, with its headquarters in Moscow. In 2012 the Russian Post delivered more than 2.4 billion pieces of mail and accounted for more than 54 million parcels and more than 100 million in remittances. In March 2013 a presidential decree signed by President Vladimir Putin included the Russian Post in a list of so-called strategic enterprises.
Pos Malaysia Berhad is a postal delivery service in Malaysia, with history dating back to early 1800s.
The London Penny Post was a premier postal system whose function was to deliver mail within London and its immediate suburbs for the modest sum of one penny. The Penny Post was established in 1680 by William Dockwra and his business partner, Robert Murray. Dockwra was a merchant and a member of the Armourer and Brasiers Livery Company and was appointed a Customs Under-Searcher for the Port of London in 1663. Murray would later become clerk in the excise office of the Penny Post. The London Penny Post mail service was launched with weeks of publicity preceding it on 27 March 1680. The new London Penny Post provided the city of London with a much needed intra-city mail delivery system. The new Penny Post was influential in establishing a model system and pattern for the various Provincial English Penny Posts in the years that followed. It was the first postal system to use hand-stamps to postmark the mail to indicate the place and time of the mailing and that its postage had been prepaid. The success of the Penny Post would also threaten the interests of the Duke of York who profited directly from the existing general post office. It also compromised the business interests of porters and private couriers. The Penny Post was also involved in publishing various criticisms towards the British monarchy, the Duke of York in particular, which ultimately led to the takeover of the Penny Post by crown authorities. The earliest known Penny Post postmark is dated 13 December 1680 and is considered by some to be the world's first postage 'stamp'.
Afghan Post is the national postal organization of Afghanistan. It has offices in all 34 provinces of Afghanistan, and is getting close to having offices in all 364 districts. Afghan Post is responsible for providing courier services in Afghanistan. Most homes in Afghanistan, particularly in older neighborhoods and in the rural areas, still do not have street addresses. Names and other descriptions may be used in place of street addresses.
The Somali Postal Service is the national postal service of Somalia. It is part of the Federal Government of Somalia's Ministry of Communications and Technology.
Turkmenpost, is the national postal operator of Turkmenistan. The company is responsible for the delivery of mail and issuing postage stamps. It has been a member of the Universal Postal Union since January 26, 1993. Turkmenpost employs about 2,000 people and has over 146 post offices, with its headquarters in Ashgabat.
The U.S. Parcel Post stamps of 1912–13 were the first such stamps issued by the U.S. Post Office Department and consisted of twelve denominations to pay the postage on parcels weighing 16 ounces and more, with each denomination printed in the same color of "carmine-rose". Their border design was similar while each denomination of stamp bore its own distinctive image in the center (vignette). Unlike regular postage items, whose rates were determined by weight in ounces, Parcel Post rates were determined and measured by increments in pounds. The new stamps were soon widely used by industry, farmers and others who lived in rural areas. Partly owing to some confusion involving their usage, their exclusive use as Parcel Post stamps proved short lived, as regular postage stamps were soon allowed to be used to pay parcel postage rates.