Governor limits are imposed on your running Apex code based on the type of resource consumed. When a governor limit is encountered, your code is immediately terminated with an exception indicating the type of limit reached. Examples of resource types are heap (memory used during execution) and SOQL queries.
Table 4.4 lists a few of the most important governor limits. Additional governor limits are introduced later in the book.
Namespaces are used to separate and isolate Apex code and database objects developed by different vendors so that they can coexist and interoperate ...