One of the earliest known references to paperwork that served in a role similar to that of a passport is found in the Hebrew Bible. Nehemiah 2:7-9, dating from approximately 450 BC, states that Nehemiah, an official serving King Artaxerxes I of Persia, asked permission to travel to Judea; the king granted leave and gave him a letter "to the governors beyond the river" requesting safe passage for him as he traveled through their lands.

In the medieval Islamic Caliphate, a form of passport was the bara'a, a receipt for taxes paid. Only people who paid their zakah (for Muslims) or jizya (for dhimmis) taxes were permitted to travel to different regions of the Caliphate; thus, the bara'a receipt was a "traveler's basic passport."

Etymological sources show that the term "passport" is from a medieval document that was required in order to pass through the gate (or "porte") of a city wall or to pass through a territory. In medieval Europe, such documents were issued to foreign travelers by local authorities (as opposed to local citizens, as is the modern practice) and generally contained a list of towns and cities the document holder was permitted to enter or pass through. On the whole, documents were not required for travel to sea ports, which were considered open trading points, but documents were required to travel inland from sea ports.

King Henry V of England is credited with having invented what some consider the first passport in the modern sense, as a means of helping his subjects prove who they were in foreign lands. The earliest reference to these documents is found in a 1414 Act of Parliament. In 1540, granting travel documents in England became a role of the Privy Council of England, and it was around this time that the term "passport" was used. In 1794, issuing British passports became the job of the Office of the Secretary of State. The 1548 Imperial Diet of Augsburg required the public to hold imperial documents for travel, at the risk of permanent exile.

A rapid expansion of railway infrastructure and wealth in Europe beginning in the mid-nineteenth century led to large increases in the volume of international travel and a consequent unique dilution of the passport system for approximately thirty years prior to World War I. The speed of trains, as well as the number of passengers that crossed multiple borders, made enforcement of passport laws difficult. The general reaction was the relaxation of passport requirements. In the later part of the nineteenth century and up to World War I, passports were not required, on the whole, for travel within Europe, and crossing a border was a relatively straightforward procedure. Consequently, comparatively few people held passports.

During World War I, European governments introduced border passport requirements for security reasons, and to control the emigration of people with useful skills. These controls remained in place after the war, becoming a standard, though controversial, procedure. British tourists of the 1920s complained, especially about attached photographs and physical descriptions, which they considered led to a "nasty dehumanization".

In 1920, the League of Nations held a conference on passports, the Paris Conference on Passports & Customs Formalities and Through Tickets. Passport guidelines and a general booklet design resulted from the conference, which was followed up by conferences in 1926 and 1927.

While the United Nations held a travel conference in 1963, no passport guidelines resulted from it. Passport standardization came about in 1980, under the auspices of the International Civil Aviation Organization (ICAO). ICAO standards include those for machine-readable passports. Such passports have an area where some of the information otherwise written in textual form is written as strings of alphanumeric characters, printed in a manner suitable for optical character recognition. This enables border controllers and other law enforcement agents to process these passports more quickly, without having to input the information manually into a computer. ICAO publishes Doc 9303 Machine Readable Travel Documents, the technical standard for machine-readable passports. A more recent standard is for biometric passports. These contain biometrics to authenticate the identity of travellers. The passport's critical information is stored on a tiny RFID computer chip, much like information stored on smartcards. Like some smartcards, the passport booklet design calls for an embedded contactless chip that is able to hold digital signature data to ensure the integrity of the passport and the biometric data.

Historically, legal authority to issue passports is founded on the exercise of each country's executive discretion (or Crown prerogative). Certain legal tenets follow, namely: first, passports are issued in the name of the state; second, no person has a legal right to be issued a passport; third, each country's government, in exercising its executive discretion, has complete and unfettered discretion to refuse to issue or to revoke a passport; and fourth, that the latter discretion is not subject to judicial review. However, legal scholars including A.J. Arkelian have argued that evolutions in both the constitutional law of democratic countries and the international law applicable to all countries now render those historical tenets both obsolete and unlawful.

Under some circumstances some countries allow people to hold more than one passport document. This may apply, for example, to people who travel a lot on business, and may need to have, say, a passport to travel on while another is awaiting a visa for another country. The UK for example may issue a second passport if the applicant can show a need and supporting documentation, such as a letter from an employer.

National conditions

Many countries issue only one passport to each national (an exception is the Family Passport, see below under "Types"). When passport holders apply for a new passport (commonly, due to expiration of an old passport or lack of blank pages), they may be required to surrender the old passport for invalidation. In some circumstances an expired passport is not required to be surrendered or invalidated (for example, if it contains an unexpired visa).

Under the law of most countries, passports are government property, and may be limited or revoked at any time, usually on specified grounds, and possibly subject to judicial review. In many countries, surrender of the passport is a condition of granting bail in lieu of imprisonment for a pending criminal trial.

Each country sets its own conditions for the issue of passports. For example, Pakistan requires applicants to be interviewed before a Pakistani passport will be granted. When applying for a passport or a national ID card, all Pakistanis are required to sign an oath declaring Mirza Ghulam Ahmad to be an impostor prophet and all Ahmadis to be non-Muslims.

Some countries limit the issuance of passports, where incoming and outgoing international travels are highly regulated, such as North Korea, where general use passports are the privilege of a very small number of people trusted by the government. Other countries put requirements on some citizens in order to be granted passports, such as Finland, where male citizens aged 18–30 years must prove that they have completed, or are exempt from, their obligatory military service to be granted an unrestricted passport; otherwise a passport is issued valid only until the end of their 28th year, to ensure that they return to carry out military service. Other countries with obligatory military service, such as Syria, have similar requirements.

National status

Passports contain a statement of the nationality of the holder. In most countries, only one class of nationality exists, and only one type of ordinary passport is issued. However, several types of exceptions exist:

Multiple classes of nationality in a single country

The United Kingdom has a number of classes of United Kingdom nationality due to its colonial history. As a result, the UK issues various passports which are similar in appearance but representative of different nationality statuses which, in turn, has caused foreign governments to subject holders of different UK passports to different entry requirements.

Multiple types of passports, one nationality

The People's Republic of China (PRC) authorizes its Special Administrative Regions of Hong Kong and Macau to issue passports to their permanent residents with Chinese nationality under the "one country, two systems" arrangement. Visa policies imposed by foreign authorities on Hong Kong and Macau permanent residents holding such passports are different from those holding ordinary passports of the People's Republic of China. A Hong Kong Special Administrative Region passport (HKSAR passport) permits visa-free access to many more countries than ordinary PRC passports.

The three constituent countries of the Danish Realm have a common nationality. Denmark proper is a member of the European Union, but Greenland and Faroe Islands are not. Danish citizens residing in Greenland or Faroe Islands can choose between holding a Danish EU passport and a Greenlandic or Faroese non-EU Danish passport.

Special nationality class through investment

In rare instances a nationality is available through investment. Some investors have been described in Tongan passports as 'a Tongan protected person', a status which does not necessarily carry with it the right of abode in Tonga.

Passports without sovereign territory

Several entities without a sovereign territory issue documents described as passports, most notably Iroquois League, the Aboriginal Provisional Government in Australia and the Sovereign Military Order of Malta. Such documents are not necessarily accepted for entry into a country.

Validity