What are the Limitations of Apex?

Apex radically changes the way that developers create on-demand business applications, but it is not currently meant to be a general purpose programming language. As of this release, Apex cannot be used to:

Render elements in the user interface other than error messages
Change standard functionality—Apex can only prevent the functionality from happening, or add additional functionality
Create temporary files
Spawn threads

Tip

All Apex scripts run on the Force.com platform, which is a shared resource used by all other organizations. To guarantee consistent performance and scalability, the execution of Apex is bound by governor limits that ensure no single Apex execution impacts the overall service of Salesforce.com. This means each Apex script is limited by the number of operations (such as DML or SOQL) that it can perform within one transaction.

All Apex trigger requests return a collection that contains from 1 to 200 records. You cannot assume that your code only works on a single record at a time. Therefore, you must implement programming patterns that take bulk processing into account. If you do not, you may run into the governor limits.