Street and market photography is generally fine in most countries, but the comfort level varies enormously, so read the room. Tourist areas, markets and public squares usually pose no problem, though vendors sometimes expect you to buy something or ask before photographing their stall up close.
Where you need real caution is anything official: airports, border posts, military installations, police, bridges and government buildings are sensitive in many countries and photographing them can get you questioned or worse. Some countries also restrict drone use heavily or require permits.
Religious sites are a category of their own. Many allow photos outside but not inside, or ban photography during prayers and ceremonies. Look for posted signs, and if there are none, ask a caretaker.
As a rule of thumb, if locals around you are not taking photos of something, pause and ask why. Checking your destination's official tourism or embassy guidance before travel is worth the five minutes.