Royal Mail Group Limited, trading as Royal Mail, is a British postal service and courier company. It is owned by International Distribution Services. It operates the brands Royal Mail (letters and parcels) and Parcelforce Worldwide (parcels). Formed in 2001, the company used the name Consignia for a brief period but changed it soon afterwards. Prior to this date, Royal Mail and Parcelforce were (along with Post Office Counters Ltd) part of the Post Office, a UK state-owned enterprise the history of which is summarised below. Long before it came to be a company name, the 'Royal Mail' brand had been used by the General Post Office to identify its distribution network (which over the centuries included horse-drawn mail coaches, horse carts and hand carts, ships, trains, vans, motorcycle combinations and aircraft).

The company provides mail collection and delivery services throughout the UK. Letters and parcels are deposited in post or parcel boxes, or are collected in bulk from businesses and transported to Royal Mail sorting offices. Royal Mail owns and maintains the UK's distinctive and iconic red pillar boxes, first introduced in 1852 (12 years after the first postage stamp, Penny Black), and other post boxes, many of which bear the royal cypher of the reigning monarch at the date of manufacture. Deliveries are made at least once every day except Sundays and bank holidays at uniform charges for all UK destinations. Royal Mail generally aims to make first class deliveries the next business day throughout the nation.

For most of its history, the Royal Mail was a public service, operating as a government department or public corporation. Following the Postal Services Act 2011, Royal Mail Group Limited became a wholly owned subsidiary of a new holding company, Royal Mail plc; a majority of the shares in Royal Mail plc were floated on the London Stock Exchange in 2013. Nine years later Royal Mail plc was renamed International Distribution Services (IDS; of which Royal Mail Group Limited remains a wholly owned subsidiary). In April 2025, IDS was acquired by EP Group, a Czech-based company owned by Daniel Křetínský, for a value of £3.6 billion after agreeing legally binding undertakings with the UK government. The government has retained a so-called golden share. The deal marked the first time the Royal Mail was under foreign ownership.

The Royal Mail can trace its history back to 1516, when Henry VIII established a "Master of the Posts", a position that was renamed "Postmaster General" in 1710.

Upon his accession to the throne of England at the Union of the Crowns in 1603, James VI of Scotland moved his court to London. One of his first acts from London was to establish the royal postal service between London and Edinburgh, in an attempt to retain control over the Scottish Privy Council.

The Royal Mail service was first made available to the public by Charles I on 31 July 1635, with postage being paid by the recipient. The monopoly was farmed out to Thomas Witherings.

In the 1640s, Parliament removed the monopoly from Witherings and during the Civil War and First Commonwealth the parliamentary postal service was run at great profit for himself by Edmund Prideaux (a prominent parliamentarian and lawyer who rose to be attorney-general). To keep his monopoly in those troubled times Prideaux improved efficiency and used both legal impediments and illegal methods.

In 1653, Parliament set aside all previous grants for postal services, and contracts were let for the inland and foreign mails to John Manley. Manley was given a monopoly on the postal service, which was effectively enforced by Protector Oliver Cromwell's government, and thanks to the improvements necessitated by the war, Manley ran a much-improved Post Office service. In July 1655, the Post Office was put under the direct government control of John Thurloe, a Secretary of State, best known to history as Cromwell's spymaster general. Previous English governments had tried to prevent conspirators from communicating; Thurloe preferred to deliver their post having surreptitiously read it. As the Protectorate claimed to govern all of Great Britain and Ireland under one unified government, on 9 June 1657 the Second Protectorate Parliament (which included Scottish and Irish MPs) passed the "Act for settling the Postage in England, Scotland and Ireland", which created one monopoly Post Office for the whole territory of the Commonwealth. The first Postmaster General was appointed in 1661, and a seal was first fixed to the mail.