Travel Warnings are issued when a State Department or respective government body decides, based on all relevant information, to recommend that travellers avoid travel to a certain country. Countries where avoidance of travel is recommended will have Travel Warnings as well as Consular Information Sheets. Public Announcements are a means to disseminate information about terrorist threats and other relatively short-term and/or trans-national conditions posing significant risks to the security of travelers. They are made any time there is a perceived threat. In the past, Public Announcements have been issued to deal with short-term coups, bomb threats to airlines, violence by terrorists and anniversary dates of specific terrorist events.
Suggested government bodies advisory sites
Department of Foreign affairs Canada
Foreign and Commonwealth Office UK
Australian Department of Foreign Affairs
US State Department
What does the advice really mean?
It is important to understand that what is provided is travel advice. The departments do not and cannot make decisions for people about when, where or whether they should travel. The responsibility is to help travelers make their own well-informed decisions. This applies equally to first-time holiday-makers or seasoned travelers. The travel advisories are never used to make a political statement. We try to use direct and clear language in travel advice. If there is compelling information that suggests it is not safe to travel to a country (or an area within a country), it will be reflected in a recommendation that travelers should defer or avoid all travel to that country (or area).
In other circumstances - where the threat is lower or information less specific - it will be advised that travellers defer non-essential travel. Whether travel is essential is a matter for personal judgment - based on your family or business needs, your concern for your own safety, your personal knowledge of the country or area, and many other factors. Advisories cannot weigh those factors for you, because they will differ from individual to individual. Only you can judge what is essential to you.