This may help you:
+--------------+---+-------------------------+------------------+---------------------+
| Class Type | | Can inherit from others | Can be inherited | Can be instantiated |
|--------------|---|-------------------------+------------------+---------------------+
| normal | : | YES | YES | YES |
| abstract | : | YES | YES | NO |
| sealed | : | YES | NO | YES |
| static | : | NO | NO | NO |
+--------------+---+-------------------------+------------------+---------------------+