Slough is a large town in Berkshire, England (within the historic county of Buckinghamshire), 20 miles (32 km) west of central London and 19 miles (31 km) north-east of Reading. It is in the Thames Valley and within the Greater London Urban Area at the intersection of the M4, M40 and M25 motorways. Slough had a population of 164,000 in 2018.

The A4 and the Great Western Main Line pass through the town. Crossrail is expected to allow faster journeys to central London.

Slough's population is one of the most ethnically diverse in the United Kingdom, attracting people from across the country and the world for labour since the 1920s, which has helped shape it into a major trading centre. In 2017, unemployment stood at 1.4%, one-third the UK average of 4.5%.

Slough has the highest concentration of UK HQs of global companies outside London. Slough Trading Estate is the largest industrial estate in single private ownership in Europe with over 17,000 jobs in 400 businesses. Blackberry, McAfee, Burger King, DHL and Lego have head offices in the town.

The name, which means "soil", was first recorded in 1195 as Slo. It first seems to have applied to a hamlet between Upton to the east and Chalvey to the west, roughly around the "Crown Crossroads" where the road to Windsor (now the A332) met the Great West Road. The Domesday Survey of 1086 refers to Upton, and a wood for 200 pigs, worth £15. During the 13th century, King Henry III had a palace at Cippenham. Parts of Upton Court were built in 1325, while St Mary the Virgin Church in Langley was probably built in the late 11th or early 12th century, though it has been rebuilt and enlarged several times.

From the mid-17th century, stagecoaches began to pass through Slough and Salt Hill (later absorbed into Slough), which became locations for the second stage to change horses on the journey out from London. By 1838 and the opening of the Great Western Railway, Upton-cum-Chalvey's parish population had reached 1,502. In 1849, a branch line was completed from Slough to Windsor & Eton Central, opposite Windsor Castle, for Queen Victoria's convenience.

In the 21st century, Slough has seen major redevelopment of the town centre. Old buildings are being replaced with new offices and shopping complexes. Tesco has replaced an existing superstore with a larger Tesco Extra. The Heart of Slough Project is a plan for the large-scale redevelopment of the town centre as a focus and cultural quarter for the creative media, information and communications industries. It will create a mixed-use complex, multi-functional buildings, visual landmarks and a public space in the Thames Valley. Recommendations for the £400 million project have been approved, and planning approval was given by Slough Borough Council's planning committee on 9 July 2009. Work began in 2010 for completion in 2018.

Herschel Park (known as Upton Park until 1949), named for astronomer William Herschel, is currently being relandscaped in a multimillion-pound effort to bring it back to its former Victorian era glory. The park was featured in an episode of the documentary programme Who Do You Think You Are? focusing on the TV presenter Davina McCall.

In 2010, £2 million was set aside to improve disabled access to Slough railway station in preparation for an expected increase in use during the 2012 London Olympics. Preparations were under way for the regeneration of the Britwell suburb of Slough, involving tearing down a dilapidated block of flats and the closing of the public house the Jolly Londoner in Wentworth Avenue and replacing them with new homes, as well as relocating the shopping parade in the street to nearby Kennedy Park. As part of the Heart of Slough project, construction work on a new bus station began in March 2010 following weeks of demolition work to half of the existing bus station and the removal of Compair House near the railway station; it was expected to be completed by January 2011 and was opened in May 2011, 5 months behind schedule.