Hong Kong is an international destination with reasonably open access for nationals of many countries; however some may require visa before entry. The details of visa requirements and visa-free length of stay may be found on the Hong Kong SAR government website.
Special arrangements pertain to Chinese nationals entering from mainland China, see here
For entry to Hong Kong of overseas Chinese and Chinese residents of Taiwan: see here
In case of need of supporting document for visa application, please contact us by e-mail at firstname.lastname@example.org.