During the past several decades, there have been major changes within most Western countries in people's attitudes toward sex, and in sexual behaviour. For people who have lived throughout this period, the changes have seemed quite remarkable. Until the early twentieth century, people in most Western countries did not have permissive attitudes regarding sexuality. For the most part, young people were expected to wait until marriage before having sexual intercourse. Of course, some premarital sex did occur, and prostitution was not rare. However, sexual behaviour was relatively restricted. As the twentieth century progressed, there was a gradual trend toward liberalization of attitudes toward sex. However, this trend was greatly speeded after 1960, when the first birth control pills became available. These contraceptive pills made it possible for women to engage in sexual intercourse without much risk of an unwanted pregnancy. As a result, many women were more willing to have premarital sex than was previously the case. Also during the 1960s, Western countries were reaching high levels of wealth and education. A new and very large generation of young people was approaching adulthood, and there was a mood of rebellion against traditional norms. There was an increase in the number of people who engaged in sex before marriage, and also a greater openness about such behaviour. By the 1970s, sexual attitudes had become quite liberal, and many young people were quite promiscuous in their sexual behaviour. However, this pattern reversed somewhat during the 1980s. There was increased concern about sexually transmitted diseases, including AIDS, moreover, many young women had been uncomfortable with the idea of unrestricted sexual behaviour. As a result, sexual attitudes became slightly more conservative during the 1980s and 1990s, although they remained much more liberal than in previous decades. In the early twenty-first century, most young people in Western countries begin having sex during their high school years, although some people wait until they are considerably older. Some young people are promiscuous, but most engage in monogamous relationships that typically last for a period of several months or a few years. When one relationship ends, another usually begins soon after. This pattern usually continues until marriage. After marriage, most people have sex exclusively with their spouse, however, some people do commit adultery. Sexuality has changed a great deal in recent decades. It will be very interesting to see how people's sexual attitudes and behaviour will change in the future.