Depth of field
Scherptediepte · Lens & optics
The part of the image that appears sharp.
Shallow depth of field (wide aperture, long focal length, close distance) gives that familiar bokeh background. Deep depth of field (narrow aperture, short focal length, far distance) keeps everything sharp. For landscape you might use f/8-f/11, for portrait f/1.8-f/2.8 - but what you want to say determines your choice.
Tools that help with this: