Job sharing involves two or more employees sharing the responsibilities of a full-time role. They split the hours and tasks between them.
Sue and John are job share partners who split the working week between them.
☆ Note: An alternative is for both to work the full day to aid with updates and knowledge
transfer.
Job-sharing is a flexible work arrangement where two or more individuals share the responsibilities and workload of a single, full-time position. Each job share partner typically works on designated days or hours, allowing for a seamless transition and continuity of tasks while promoting a better work-life balance."
For more reading have a look at the Working Families site.