Air-entraining agents are additives used in concrete and mortar to introduce tiny air bubbles into the mix. These microscopic bubbles improve the material's resistance to freeze-thaw cycles, enhancing durability and preventing cracking. They also help improve workability, making the mixture easier to handle and apply. Commonly used in construction, air-entraining agents can be natural or synthetic. Examples include sodium lauryl sulfate and vinyl acetate. The presence of these agents is particularly beneficial in regions with harsh winter conditions, as they help protect structures from damage caused by water expansion during freezing.