Hasidism did not renew Judaism’s basic principles. Rather, Hasidism is based on Kabbalah, and transforms its teachings into practice, a method which speaks to the spiritual longings of much of the modern Jewish world, from great-standing leaders to the newly-observant. Hasidism emphasized the omnipresence of God, necessitating relating to all aspects of life with full affirmation, thereby extracting the Godliness in everything, along with possessing the awareness that everything can be used for the service of God. Hasidism emphasizes man’s continual spiritual ascension, both by acquiring knowledge of the Torah, and by working on one’s soul, achieving overall spiritual transcendence.
For these reasons, Hasidism addressed personal sadness, personal fasting, and the like as causing spiritual crises instead of spiritual growth, so instead, the movement offered more positive ways to achieve a heightened soul. For example, Hasidism placed prayer as central to the service of, and relationship with God, and did so by employing expanded forms of prayer, breaking away from mere straight-word recitation, and perhaps accompanied by modest singing. Hasidism revitalization was based in encouraging emotional expression, especially via lively, engaging song and dance, all within the context of a very tight-nit Hasidic community in which members assist each other with all aspects of life, including worship.
A critical change was in the style of the prayer: the Hasidim replaced the Ashkenaz prayer order with the Sefard method, which is based on Kabbalah.
Each Hasidic sect’s Rebbe (sometimes called an Admor, [which means "Our Lordship, Our Teacher, Our Rabbi”]) is considered a supreme spiritual personality, a person who has reached the highest levels of God's service and is capable of enlightening others about his worldview. Hasidim believe their Rebbe is spiritually supportive of his adherents, both directly and indirectly through his prayers and work. The Rebbe also serves as the center of their Hasidic sect, the person to whom they come with any problem in order to receive sound advice, be saved from their problems by the Rebbe’s prayers, or be assisted in any other way. Many of the Rebbes were famous for being "miracle workers,” known for their abilities to effectively pray on behalf of others. Although this approach was not new (there is a Talmudic concept of the "talmid hakham” - a noble, learned person), nonetheless it aroused harsh criticism among the Mitnagdim. They took issue with the miracle-working qualities of Rebbes, especially since they claimed that Hasidic practices were not worthy of this term. Yet ironically, many of the greatest opponents also benefited from Hasidic Rebbe blessings.
During Hasidism’s early period, the majority of Rebbes were chosen via meritocracy, which later evolved into inherited positions, creating hereditary dynasties whose leaders are akin to royalty.
The influence of [the anti-semitic elements] of the Enlightenment, the French Revolution, Communism, and later of course the Holocaust, led to the destruction of great centers of Hasidic life, in many cases where their presence was most entrenched. Most of the Hasidic dynasties perished during the Holocaust - leaders together with their followers. However, a number of Hasidic sects did survive.
Among these are the Belz (now in Galicia), the Vizhnitz and Sanz (who came to Hungary), the Gur (Russian Poland) and the Chabad Hasidim, and dozens of other dynasties with smaller followers. Today, all of these sects are found mainly in Israel and the United States.
The Hasidic movement created vast literature, ranging from involved theological works to folk stories about acts of righteous Hasidim. Hasidism also created melodies loved by thousands worldwide. In recent generations there has been an sweeping appreciation for Hasidism in all circles - many stories and books have been written about Hasidism over the last few decades.