The term lay-by is used in the United Kingdom and Ireland to describe a roadside parking or rest area for drivers (equivalent terms in the United States are "turnout" or "pullout"). Lay-bys can be used for hitchhiking purposes, although due to a very few cars actually driving in there, do not expect very fast hitchhiking.
Lay-bys can vary in size from a simple parking bay alongside the carriageway sufficient for one or two cars only, to substantial areas that are separated from the carriageway by verges and can accommodate dozens of vehicles.
They are marked by a rectangular blue sign bearing a white letter P.
At some larger lay-bys mobile catering is provided by vendors operating from converted caravans, trailers or coaches. These facilities generally offer much better value for money than roadside restaurants and therefore tend to be popular with truckers.