What are the visa & residency requirements in Istanbul?

"In order to visit Istanbul, visitors must obtain a visa prior to their arrival. The process of applying for a visa involves submitting an application form, providing a valid passport, and paying the applicable visa fee. Depending on the purpose of the visit, additional documents may be required. In order to obtain residency in Istanbul, Turkey, applicants must submit an application form, provide a valid passport, and provide proof of sufficient financial resources. Depending on the purpose of the residency, additional documents may be required. Applicants may also be required to attend an interview with the relevant authorities. Once the application is approved, the applicant will receive a residence permit," mentioned another expat when asked about moving to Istanbul, Turkey.