Egham is a university town in the Borough of Runnymede in Surrey, England, approximately 19 miles (31 km) west of central London. First settled in the Bronze Age, the town was under the control of Chertsey Abbey for much of the Middle Ages. In 1215, Magna Carta was sealed by King John at Runnymede, to the north of Egham, having been chosen for its proximity to the King’s residence at Windsor. Under the Dissolution of the Monasteries in the early 16th Century, the major, formerly ecclesiastical, manorial freehold interests in the town and various market revenues passed to the Crown.

In the 17th and 18th centuries, Egham became a stop on coaching routes between London and many places to the west. The importance of this shrank from the building of the Western and South Western Railways but was for many decades offset by the stark growth in the population of London and the country at large. Egham station was opened in 1856 on the line from Waterloo to Reading and services are operated today by South Western Railway. The town is west of the M25 motorway, accessible via junction 13.

The campus of Royal Holloway, University of London is 1 mile (2 km) to the west of Egham town centre, close to Englefield Green.

Egham predates c.670 AD when Chertsey Abbey was founded; one of the earliest Chertsey charters mentions Egeham. The place-name means "Ecga's farm".

Egham appears in the Domesday Book of 1086 as Egeham. It was held by Chertsey Abbey and kept by that institution after the conquest when its assets were: 15 hides; 12 ploughlands, 120 acres of meadow, together with woodland, 'herbage and pannage' worth 75 hogs. It rendered one of the largest sums in Surrey to its feudal overlords per year, £30 10s 0d.

The village of Egham was, before 19th-century losses, an ancient parish raping land totalling 7,435 acres in the counties of Berkshire (briefly) and Surrey; incorporating Egham, Egham Hill, Cooper's Hill, Englefield Green, Virginia Water, Shrubs Hill, Runnymede, Egham Hythe, and a considerable portion of Windsor Great Park.[8] In the medieval period it was divided into four roughly equal tythings:

• Hythe (which was on fairly similar boundaries to Egham Hythe)
• Town
• Strode (later also known as Stroude), but which now denotes a much smaller, and inconsistent area
• Englefield, which is partly Englefield Green, partly Virginia Water
• The manor of Egham, which includes Runnymede, belonged formerly and in 1215 to Chertsey Abbey, and after the Dissolution of the Monasteries (around 1540) became the property of the Crown, though granted to various tenants (holders) at different times.

Magna Carta was sealed at nearby Runnymede in 1215, and is commemorated by a memorial, built in 1957 by the American Bar Association, at the foot of Cooper's Hill (a small rise adjacent to the Thames floodplain, immortalised in verse by poets including John Denham ("Cooper's Hill") and Alexander Pope ("Windsor Forest")). A Sculpture by artist David Parfitt portraying King John and Robert Fitzwalter in the act of sealing Magna Carta can be found in Church Road in the centre of town.

Another memorial at the top of the hill in nearby Englefield Green, the Air Forces Memorial commemorates Commonwealth air force personnel killed during the Second World War but who have no known grave. It was the first new-built British building to be listed in the post-war era. The memorial is administered by the Commonwealth War Graves Commission and freely open to the public year-round. It has excellent views towards London, Windsor and the Surrey Hills, as well as being a place of quiet contemplation and reflection.

Egham at one time held horse races which took place at the Runnymede meadow, which interfered with the Inclosure Act of 1814 (54 G. III, c. 153) and the consequent award made in 1817, which divided up the meadow, as the Act stipulated that any enclosures which should interfere with the holding of Egham races at the end of August upon its usual course must be removed every year. In 1836 the races were presided over by William IV, who gave a plate to be run for at the meeting, which coincided with festivities at Windsor for his daughter's marriage. The races ceased in 1884.

Other than two forming the hub of today's Virginia Water (including Wentworth), the principal properties were 'Egham Manor and Park', 'Egham Wick', 'Kenwolde Court', 'Markwood', 'Kingswood' and 'Alderhurst' for a time home of Lord Thring.

Parts of Egham have featured in national and international news in the 21st century. On 12 September 2007 a case of foot-and-mouth disease was found in Egham, 12 miles (19 km) from the previous outbreak found in early August 2007. In December 2008, Egham was at the centre of a controversy due to possible traffic impact on the three level crossings in the town to be kept in situ under the abandoned Heathrow Airtrack project. Occasional flooding of Runnymede and parts of Egham Hythe have taken place following exceptional Thames Valley winter rainfall. Units of the army were deployed to assist with defences and dealing with damage from flooding in the 2013-14 winter storms.