Reform Judaism is the most popular Jewish denomination in the United States today. The movement runs camps, youth groups, more than 900 synagogues, and several Jewish day schools. Reform congregations typically incorporate English (or whatever the native language is around the congregation) into the worship service, and may have musical accompaniment. Reform Judaism began in 1800s Germany as people strove to create a Judaism that was more in keeping with contemporary sensibilities. This involved changing the nature of prayer services and changing or discarding some Jewish practices, such as the dietary laws (kashrut) and other ritual behaviors. Over time, some of those practices have made a resurgence among some Reform Jews.
As is true for all other denominations, there is no one set of Reform practices and beliefs. Reform Jews might go to temple every Shabbat, eat pork or keep a strictly kosher kitchen, pray in Hebrew or pray in the vernacular. However, Reform Judaism supports its congregants in making the ritual choices that they think are appropriate based on their understanding of Jewish tradition. Reform congregations are egalitarian, and the movement is welcoming towards LGBT people.
Like many Reconstructionist and some Conservative synagogues, Reform temples typically celebrate one day of Jewish festivals instead of the two days that had historically been celebrated in the Diaspora. They are also likely to have confirmation ceremonies for teenagers (often at age 16 or following the 10th grade) in addition to bar and bat mitzvah celebrations, a custom which has been adopted by some other movements as a way of keeping young people in Hebrew school longer, but originated within the Reform movement.
The movement places an emphasis on working towards social justice, and operates the Religious Action Center, which advocates on a variety of social justice issues on the behalf of Reform Judaism.
Reform Judaism welcomes interfaith families, and some (but not all) Reform rabbis will perform interfaith weddings. They consider children of either a Jewish father or a Jewish mother to be fully Jewish, provided they are brought up in the Jewish tradition. In addition, in many areas there are Reform-trained mohelim (trained professionals who perform ritual circumcision) who can help with the birth rituals for baby boys who would not be served by mohels from other denominations.
The Union for Reform Judaism has called on congregations to invite people to convert and they are generally supportive of conversations of non-Jewish spouses and partners. Their welcoming attitude towards intermarriage and conversions has helped the movement grow at a time when interfaith marriages are increasing and people might find it harder to be accepted — or find that they have more hoops to go through — at synagogues of other denominations. However, like in other denominations, someone married to a non-Jew cannot become a rabbi in the Reform movement.