Charismatic Christianity (also known as Spirit-filled Christianity) is a form of Christianity that emphasizes the work of the Holy Spirit, spiritual gifts, and modern-day miracles. Practitioners are often called Charismatic Christians or renewalists. Although there is considerable overlap, Charismatic Christianity is often categorized into three separate groups: Pentecostalism, the Charismatic Movement, and Neo-charismatic movement. According to the Pew Research Center, Pentecostals and Charismatic Christians numbered over 584 million or a quarter of the world's 2 billion Christians in 2011.