When should we use innodb engine?

I am newbie to MySQL and don't know much about MySQL table engines.  Can you explain, when should we use InnoDB Engine?

InnoDB tables are ideal for the following scenarios, among others:

• Update-intensive tables: The InnoDB storage engine is particularly adept at handling multiple simultaneous update requests.
• Transactions: The InnoDB storage engine is the only standard MySQL storage engine that supports transactions, a requisite feature for managing sensitive data such as financial or user registration information.
• Automated crash recovery: Unlike other storage engines, InnoDB tables are capable of automatically recovering from a crash. Although MyISAM tables can also be repaired after a crash, the process can take significantly longer.

As of version 3.23.44, InnoDB supports foreign keys, a feature not slated to be available to other storage engines until version 5.1.