Entering and staying in the Schengen area
You must at all times meet the requirements for travelling without a visa. For example, you must have enough money for a return ticket. Are you travelling with a visa? Then you must also have travel insurance that covers medical expenses.
If you do not meet these requirements you may be refused entry to a Schengen country or the Schengen area.
Extending a visa
You can only extend a short-stay visa in emergencies, for example if you become ill. Strict conditions apply.