Stwnsh (Mash, ) is a strand of Welsh-language children's television programming on S4C, aimed at children between the ages of 7 to 13.
was launched on Monday 26 April 2010, replacing the former Welsh-language children's strand, . is broadcast on S4C every weekday, from 5.00pm to 6.00pm, and on Saturdays as from 8.00am to 10.00am.
The programmes shown as part of this service include both brand-new programmes and programmes that were previously shown as part of .
The long-running programme was scrapped by S4C to make way for service, although the final episode of , was not broadcast until Sunday 30 May 2010, just over a month after the launch of the service.