Proselytization is the act of attempting to convince someone to convert their religion. However especially in recent times, the term has taken on negative connotations associated with historical forced conversions, so the term "Missionary" is frequently used instead. The term "missionary work" can and does encompass far more than proselytization, though it is most often done with at least some expectation of spreading the faith.
Acceptance of missionaries and conversion varies widely. Buddhism, Christianity, and Islam are the most approving, while others are less so, and some like Judaism see the practice of seeking conversion as actively sinful. Historically, the political threat of foreign missionaries played a large role in Japan's decisions to close themselves off from the outside world in the 1600s, and then after being forced to reopen in the 1850s, to embrace Shinto as the state religion.
Most depictions of missionaries will likely be in their modern forms: that of people going door to door seeking conversations about religion akin to Jehovah's Witnesses or Mormons.
