Before travelling abroad, contact the authorities of your country of destination to find out what travel document you will need, if you need to obtain a visa and if your passport needs to be valid for a certain period of time after you have left the country.
You can travel to the EU countries and certain other European countries with an identity card. As a rule, travel documents are not checked at the border in Schengen countries, though you must show it if requested. A travel document is usually not needed when travelling in the Nordic countries, but you must be able to prove your identity if requested.
On all current passports, the first two characters of the passport number are letters and the remaining seven characters are numbers. This information is useful when you are filling in an ESTA form or applying for a visa.