Offaly borders seven counties: Galway, Roscommon, Tipperary, Laois, Westmeath, Kildare and Meath.

The highest point is Arderin (Irish: Ard Éireann) in the Slieve Blooms at 527 metres (1,729 feet).

The River Brosna runs across the county from Lough Owel in Westmeath to Shannon Harbour.

The county consists of approximately 420 square kilometres (160 sq mi) of peatland which is 21% of Offaly's total land area.

For the 2011 general election, some electoral divisions in South Offaly were part of Tipperary North.

One of the earliest known settlements in County Offaly is at Boora Bog which dates back to the Mesolithic era.

The county itself was formed following the Tudor plantations of Laois and Offaly in an attempt by the Roman Catholic English Crown under Queen Mary I to expand its sphere of influence in Ireland which had declined following the Norman Conquest of Ireland.

Both Laois (Leix) and Offaly (Uí Failghe) were petty kingdoms in Gaelic Ireland located just outside the Pale (a region around Dublin and the mid-east of Ireland that remained loyal to the English Crown following the Norman Conquest).

The older kingdoms of Leix and Uí Failghe are not coterminous with the present-day counties that were formed.

The Kingdom of Firceall ruled by the O'Molloy clan constituted much of the centre of the county.

Bord na Móna was founded in 1946 and provided employment to hundreds of people in Offaly by making peat briquettes (for home domestic use) and supplying peat to power stations operated by ESB.

With the continuing depletion of the bogs, a number of power stations have closed down in recent years.

The ESB power station at Lumcloon, Ferbane was a major employer in the midlands but closed in 2001.

The opening of the Grand Canal in the 18th century brought prosperity to towns such as Banagher and Tullamore.

Both towns were important stops on the Dublin to Limerick navigation which supported a number of industries and brought cheap and efficient water transport to the county in that era.

The Celtic Tiger also brought an increase in economic activity to Offaly with business enterprise and industrial parks opening in Birr, Edenderry and Tullamore.

Many people particularly in the east of the county are within an easy commuting distance to Dublin where many find employment.

Both stations are on the main Dublin–Westport/Galway railway line with regular trains serving the area, especially for Dublin commuters.

The southern and western baronies of Garrycastle, Ballyboy, Eglish, Ballybritt, and Clonlisk have no train stations.

The majority of the baronies of Eglish and Ballybritt have a more than 25-minute drive to the nearest train station, be it Clara, Tullamore, or Ballybrophy in neighbouring Laois.

There are no main national primary routes in the county; the M6 skirts it to the north and the M7 to the south through Moneygall.

Traditionally this was an important route for transport, communication and trade between Dublin, Limerick and the midlands of Ireland.

The Midland Tribune, based in Birr, covers local news in the west and south of the county as well as parts of northern Tipperary including the towns of Birr, Roscrea and Nenagh and surrounding areas.

Offaly GAA has 44 clubs in various communities, contesting the traditional sports of football and hurling.

The football team is remembered for Séamus Darby's goal in the dying minutes of the 1982 All-Ireland SFC final, when Offaly took the title by one point and denied opponent Kerry what would have been a historic (having never before occurred, and not occurring until 2019) five consecutive titles.

Previously they played in the A Championship and League of Ireland B Division Other popular sports in the county include rugby and golf.