Most household and small-scale appliances such as televisions, laptops, PCs and washing machines require dc current supplies or constant voltages as a source of external energy required to create electric signals needed for their function.
Converting alternating currents (AC) supplied by commercial power sources into direct currents (DC) that are needed for most electrical circuits is an easier process than converting DC to AC currents. This is exactly what AC adapters do. Often for small appliances, AC adapters are built into the battery chargers that are used for mobile phones and laptop computers. In larger appliances like televisions, the adapters are inbuilt.
This video should make all this clear!