Today's date is shown above in words and in ISO 8601, together with the figures that usually follow the question: which day of the year it is, which ISO week, which quarter, and how many days are left before the year ends. Everything is read from your own device, so it is always the date where you are.
The same day, written several ways
The date you see written as 03/04 means the third of April in most of the world and the fourth of March in the United States. ISO 8601 removes the ambiguity by putting the year first, which is why it appears alongside the plain form here — see date formats by country.
The figures underneath the date
Day of year counts from 1 January and runs to 365 or 366; ISO week runs Monday to Sunday with week 1 containing the first Thursday. They are covered in day of year and Julian day and ISO week numbers. For arithmetic on dates, use the date calculator.