Microsoft, Yahoo and Google all have significant operations in Ireland and employ about 3,700 staff between them.

• Microsoft has the longest established roots in Ireland, having first opened here in 1985 to manufacture software discs that were shipped to European markets. Just as Microsoft has expanded and changed its business models, so too have its Irish operations. There are now 1,200 direct employees and 500 contractors in four buildings in Sandyford, Co Dublin, carrying out a range of functions for the European, Middle East and African (EMEA) markets, from supply chain to product development. Paul Rellis, managing director of Microsoft Ireland, says that Ireland was the first location outside of the US to take on a significant development role for the core Windows product.

• Google came to Ireland in 2003 and employs more than 1,500 staff in two buildings on Barrow Street, Dublin 4, which is its largest base outside the US. The Irish operations are the internet giant's operations centre for its EMEA activities. The bulk of the staff provide support to Google customers buying advertising in countries in those markets. In common with its Californian headquarters the style is relaxed, with no set hours for staff and plenty of on-site amusements such as table football. The company is seen as a good employer in the technology sector and is known to pay above market rates to attract staff.

• Yahoo's presence in Dublin came about through its acquisition of internet advertising company Overture, who employed 200 in the Republic. In 2005 it announced details of an IDA-backed expansion, which, it said, would bring employment to 700 by 2010. Its European operations HQ is now located in Dublin's East Point and has about 500 staff, although the proposed Microsoft acquisition and recent poor performance mean the planned expansion is unlikely to materialise.