The Great Spotted Woodpecker is the most common and widespread woodpeckers in the Netherlands.
It has black and white plumage, a prominent oval-shaped white patch on each wing and a red underbelly (trousers). 
Males have a red patch on the rear of the head which females don't have.
Juveniles can be identified by their red crown which they loose after their first mould (August - September).

1st photo: A juvenile. In my yard, Hilversum, The Netherlands, 9 June 2022
2nd photo: A male and a juvenile. In my yard, Hilversum, The Netherlands, 9 June 2022
3rd & 4th photo: A male. Spandersbos, Hilversum, The Netherlands, 28 April 2021
5th photo: A male. Spandersbos, Hilversum, The Netherlands, 4 April 2018