All season is a manufacturer determination that their tires are capable for performing in year round weather. This normally means that sacrifices have been made to allow them to perform at below freezing conditions . The idea is to design a tire in which these sacrifices are small enough that the benefit of not having to change tires for winter outweighs the cost. Technology has improved to the point that many current all season tires perform at the level a high performance tire would have in the past. Though in comparison to contemporary tires, the technology for other types of tires has also improved and so all season tires are still a convenience measure.
Often these tires are aimed at a target market that is more interested in utility over performance and therefore they are also designed for quiet comfortable ride.
An early tire that was marketed as an all season tire was the Goodyear Tiempo and it is from that marketing campaign that the concept of all season tires would grow. With the slogan "Snow tire, rain tire, sun tire; one tire does it all!", it was a very successful tire and other companies would look to develop their own products in this range.