County ins and outs:
Ins: Ravi Rampaul (Surrey), Mitchell Santner (Overseas), Duanne Olivier (Overseas), Safyaan Sharif (One-Day Cup & Vitality Blast), Wahab Riaz (Vitality Blast)
Outs: Tom Wood, Greg Cork, Tom Milnes (all released)
Ins: Will Smith (Hampshire), Nathan Rimmington (Overseas), Aiden Markram (Overseas), Tom Latham (Overseas), Axar Patel (Overseas)
Outs: Paul Coughlin (Nottinghamshire), Graham Onions, Keaton Jennings (both Lancashire)
Other news: Paul Collingwood has signed a one-year contract extension
Ins: Feroze Khush (Youth), Matt Coles (Kent), Peter Siddle (Overseas for the first five Championship matches), Neil Wagner (Overseas mid May to end of July), Adam Zampa (Overseas for Blast)
Outs: Chris Silverwood (Head Coach has been appointed England fast bowling coach), Kishan Vilani (released)
Winter news: Anthony McGrath has been confirmed as Head Coach, Dimi Mascarenhas has been confirmed as assistant coach.
Ins: Matt Maynard has re-joined as batting consultant. Shaun Marsh has signed a two-year deal. Usman Khawaja (Vitality Blast)
Outs: Jaques Rudolph (Retired), Will Bragg (Retired)
Other news: Colin Ingram has become limited-overs captain, with Michael Hogan continuing to lead the Specsavers County Championship side.
Ins: Ryan Higgins (Middlesex), Andrew Tye (Overseas for Blast), Daniel Worrell (Overseas)
Outs: Patrick Grieshaber and Brandon Gilmour (released), Phil Mustard.
Ins: Sam Northeast (Kent), Chris Sole (Youth), Hashim Amla (overseas), Dale Steyn (Overseas), Colin Munro (Vitality Blast), Mujeeb Ur Rahman (Vitality Blast)
Outs: Will Smith (Durham), Michael Carberry (Leicestershire)
Ins: Ollie Robinson (Youth), Harry Podmore (Middlesex), Heino Kuhn (Overseas), Matt Henry (Overseas), Carlos Brathwaite (Vitality Blast)
Outs: Adam Ball, Hugh Bernard, Charlie Hartley (all released) Matt Coles (Essex), Sam Northeast (Hampshire).
Sam Billings has been confirmed as Club Captain.
Ins: Keaton Jennings and Graham Onions (both Durham), Josh Bohannon (Youth), Liam Hurt, James Faulkner (T20 Blast), Joe Mennie (Overseas)
Outs: Kyle Jarvis (released), Luke Proctor (Northamptonshire)
Contract news: Shivnarine Chanderpaul has signed a new one year contract for 2018
Captaincy news: Liam Livingstone has been named the new Club Captain
Ins: Michael Carberry (Hampshire), Ateeq Javid (Warwickshire), Tom Taylor (Derbyshire), Mohammad Abbas, Sohail Khan (Overseas), Mohamed Nabi (Overseas for Vitality Blast), Varun Aaron (Overseas cover for Abbas early season).
Outs: Clint McKay (released), Will Fazakerley (retired)
Coaching staff: Paul Nixon has replaced Pierre de Bruyn with John Sadler as his assistant. Graeme Welch has left to rejoin Warwickshire.
Ins: Ashton Agar (Vitality Blast), Hilton Cartwright, Dwayne Bravo (Vitality Blast).
Outs: Ryan Higgins (Gloucestershire), Harry Podmore.
Ins: Brett Hutton (Nottinghamshire), Luke Proctor (Lancashire), Doug Bracewell (Overseas), Rory Kleinveld (Overseas), Seekugge Prasanna (Overseas)
Outs: David Murphy (retired), Azaharulah (released)
Coaching staff: Former captain David Sales has become full-time batting coach after a part-time spell in the role.
Ins: Paul Coughlin (Durham), Chris Nash (Sussex), Ish Sophie (Vitality Blast), Will Fraine (Youth)
Outs: Brett Hutton (Northamptonshire), Chris Read (retired)
News: Steven Mullaney has been appointed as Club Captain
Ins: Finn Trenouth, Corey Anderson (Overseas for Vitality Blast)
Outs: Jim Allenby, Ryan Davies, Michael Leask (all released)
Coaching staff: Andy Hurry has returned as Director of Cricket following the departure of Matthew Maynard. Jason Kerr has become head coach.
Other news: Marcus Trescothick has signed a one-year contract extention.
Ins: Mitchell Marsh, Aaron Finch (T20 Blast), Will Jacks, Gus Atkinson (both youth, Morne Morkel (Kolpak)
Outs: Ravi Rampaul (Derbyshire), Kumar Sangakkara (retired)
Ins: Jason Gillespie has signed as coach, Rashid Khan (Overseas) has signed for the Blast, Ishant Sharma (Overseas) has signed for from 4 April to 4 June.
Outs: Chris Nash (Nottinghamshire), Steve Magoffin (Worcestershire)
Coaching Staff: Mark Davies has left his post as head coach
Ins: Alex Thomson, Colin De Grandhomme (Blast)
Outs: Ateeq Javid (Leicestershire), Mark Adair
Coaching Staff: Graeme Welch has returned as bowling coach
Captaincy: Jeetan Patel has been named as Captain in the Specsavers County Championship and Royal London One-Day Cup, Dom Sibley will be Vice Captain. Grant Elliott will continue as Birmingham Bears captain in the Blast
Ins: Alex Milton (Youth), Steve Magoffin (Sussex), Martin Guptill (Vitality Blast), Callum Ferguson (Vitality Blast).
Ins: Kane Williamson (Overseas), Cheteshwar Pujara (Overseas).
Outs: Ryan Sidebottom (retired), Will Rhodes (Warwickshire)
Other news: Billy Stanlake was signed for the Blast but later withdrawn by Cricket Australia to focus on national commitments