Hyperlinks (clickable URL) can be included in some text fields in NSP, e g descriptions and comments. Links can also be part of forms, when field is created as clickable field.
Link in ticket comment
When you click the link the browser is redirected to specified site outside NSP. If you want NSP tab to remain intact, you could use browser command to open the link in other tab or window (recommended):
•CTRL + click = open link in new browser tab
•SHIFT + click = open link in new browser window