Winter windscreen washers
— liquids with a lower freezing point, allowing operation in winter, at temperatures below zero. If you plan to drive in winter, you can only fill the washer reservoir with this composition: ordinary water or “summer” liquid will freeze and become useless at best, and at worst it can damage the washer system due to expansion and crystal formation.
Note that even among winter liquids there are brands with different freezing temperatures. Therefore, if the car is supposed to be operated in a harsh climate, it is worth making sure that the frost resistance of the selected composition will correspond to climatic conditions. See "Freezing point" for details.
Also note that most winter liquids are quite suitable for summer use; and some of them are initially positioned as all-season, especially when it comes to concentrate (see "Type"). In fact, the only obstacle to such an application is financial: winter compositions can cost significantly more than summer ones, and in the warm season it is more profitable to buy a simpler and more inexpensive liquid.