What data types have you used for storing identifiers in your projects?.

The following data types are commonly used for storing identifiers in PHP projects:

• int (integer): for numeric identifiers, such as auto-increment IDs from a database.
• string: for UUIDs or other string-based unique identifiers.

Example of usage:

// Numeric ID
$userId = 123;

// UUID
$orderId = '550e8400-e29b-41d4-a716-446655440000';

The choice of type depends on the requirements for uniqueness and the format of the identifier. Numeric IDs are simpler and more efficient for indexing, while UUIDs provide global uniqueness.