It was formed was formed in 1990 in preparation for the privatisation of the previously state-owned Scottish electricity industry the following year.
One of the biggest challenges the energy firm faced surrounded its acquisition by Iberdrola. This was agreed by the ScottishPower board in November 2006, at a cost of £11.6 billion to the Spanish firm.
It is the main supplier of electricity to central and southern Scotland, North Wales and Merseyside and supplies energy to other parts of the country.
Its Energy Networks division has more than 30,000 substations (one substation for every 100 customers), 40,000km overhead lines (once around the globe), and 70,000km underground cables. It has a workforce of 3000 based at 17 locations in the south of Scotland and 17 locations in England and Wales.
Its Energy Wholesale wing contains two companies, one of which, ScottishPower Generation Ltd, generates over 6000MW of electricity power in the UK.
ScottishPower Renewables, the largest wind-power company in the world, has a pipeline of 10,000MW in offshore wind projects across Europe, primarily in the UK.