The High Speed 2 railway line (HS2) is a proposal for a new fast railway line between London and the North with trains travelling at speeds of up to 360kph (225mph).

Initially, the Department for Transport (DfT) proposed to create the HS2 in two phases: Phase 1 being from London to the West Midlands (including Birmingham) and Phase 2 taking the line further North. In 2015, Phase 2 was split into two stages: Phase 2a will be from the West Midlands to Crewe. And Phase 2b will have two legs: one from Crewe to Manchester and the other from the West Midlands to Leeds and South Yorkshire.
The map on the right uses magenta for Phase 1, yellow for Phase 2a, red for Phase 2b.

Phase 1 will provide services between London and Birmingham. The only stations will be at London Euston, Old Oak Common, Birmingham International Interchange and Birmingham Curzon Street (which is near to the other stations in Birmingham). By providing a spur to a junction with the West Coast Main Line (north of Lichfield), it will also provide services between London and the North (e.g., Manchester). Heathrow Airport will be reached by changing trains at Old Oak Common. It is planned for Phase 1 to be completed by 2026.

Phase 2 extends the line north of Birmingham to provide a high speed line between London and places in the North. There are two legs: a western leg which has a bit finishing in Manchester and an eastern leg which has a bit finishing in Leeds.

Phase 2a is from the West Midlands to Crewe. There will one station, the station at Crewe. It is planned for Phase 2a to be completed by 2027.

Phase 2b is from Crewe to Manchester and from the West Midlands to Leeds and South Yorkshire. There will be stations at Manchester Airport, Manchester  Piccadilly, Toton (between Derby and Nottingham) and Leeds. There will also be a spur to join the West Coast Main Line south of Wigan, and a spur to join the line to Chesterfield and Sheffield Midland and a spur to Church Fenton to provide access to the East Coast Main Line. To enable a fast service between Sheffield and Leeds, a spur from the existing line North of Sheffield to rejoin the HS2 near Clayton is under consideration. It is planned for Phase 2b to be completed by the end of 2033.

The official pages about the HS2 are on the www.gov.uk web site. There's a Wikipedia page which is good.