Instagram is one of the popular apps that allow you to share your photos and videos along with transforming them with multiple filters that are present in the app.
Now one concern that arises when you are sharing your photos/videos is that it should not be visible to all those for whom it is not intended to. For this Instagram provides you an option to make them private i.e. only those whom you allow can see them. The process differs slightly depending on which phone you are using.
For iOS (Apple) users:
Once this setting is turned on, your posts will be visible only to your approved followers. All other Instagram users, other than your followers, won't be able to see any of your activities. In case, if anyone wants to do so, they'll have to send you a request. After you accept their request only then they would able to see your posts. However, your name will still appear on other photos you like/comment on. Also people send photos/videos to you even if they're not one of followers.