Before your travel please make sure your travel documents (etc. Passport, ID) are valid. Adults are eligible to travel within EU only with citizenship ID. Children must have their own passport and cannot be registered under parent’s passport as it was allowed previously.
Travel document should be valid at least 3 or 6 months after returning from holiday. Each country has it’s own terms and conditions for entering the country. You can check these terms on a web site of the ministry of foreign affairs of Slovak republic.