日记。You can write whatever you like in your diary. A diary entry is basically a record of events.

Entry = the recording of a note, normally with a date. You are accesing your diary to write about whatever you want, could be about your day or about a flower... it's your diary, you decide ! ^^

When you're writing something into a book or something thats personal. :)

It's an entry in your diary. Entry = 目