Often an idea comes to mind but after a movement it has gone. And you never can that idea back. Sometimes we want to share our thoughts, but no one has time to listen you and if you have a secret so you cannot share with everyone or you cannot trust anyone. So, get a diary and share with it everything you want. It keeps your secrets as secrets, saves your thoughts and all the things you wrote.
Diary writing is considered a good habit and a hobby too in ancient times. People wrote their daily observation, experience and incidents. Their coming generation told their children those precious and worth experience. They used paper Diaries, they bought from book store or made themselves.
In this fast and modern time no one has time to spend writing diary. To date some people, write diary but they are in a small figure. Modern people manage their diary in modern way. They use a digital diary, online or offline. For a digital diary, just browse your app market and choose your desired diary.
And modern shape of diary is blog writing but is a public forum and every blog visitor can read it. It is not very secure and safe because your data is on a risk of determination or hacking. So always choose a diary from book store.