Explain the difference between transient API and options API.

1. Options API

Purpose:

• Stores persistent data in the WordPress database (wp_options table).
• Data remains until you manually delete or update it.

When to Use:

• Site settings, plugin configurations, feature toggles.
• Data that doesn’t expire automatically.

Example:

// Save option
update_option( 'my_option', 'Hello World' );

// Get option
$value = get_option( 'my_option' );

// Delete option
delete_option( 'my_option' );

2. Transients API

Purpose:

• Stores temporary cached data in the database (or memory if object caching is enabled).
• Has a built-in expiration time.
• Automatically deleted when expired.

When to Use:

• Storing API responses, query results, or calculations that don’t need real-time refresh.
• Reducing load by caching expensive operations.

Example:

// Save transient (expires in 1 hour)
set_transient( 'my_transient', 'Hello World', HOUR_IN_SECONDS );

// Get transient
$value = get_transient( 'my_transient' );

// Delete transient
delete_transient( 'my_transient' );

Key Differences Table

💡 Quick Memory Tip:

Options API = Filing cabinet 📂 (keeps things until you throw them away)
Transients API = Sticky notes 📝 (expire and get removed automatically)