uiRecordApi

In plain words: Setting default field values on record creation in LWC means automatically pre-populating input fields with preset business values (like default statuses, current dates, or parent IDs) when the component initializes, so users don't have to enter repetitive information manually. Pre-populating standard or custom fields during record creation speeds up data entry, reduces human error, and improves overall user satisfaction. Using Lightning Data Service (LDS) through the lightning/uiRecordApi module allows you to create records directly on the client side with custom default values—without writing custom Apex insertion code.

In plain words: Autofill in Lightning Web Components (LWC) automatically predicts, completes, or populates related form inputs as the user types. This is typically done either by filtering client-side suggestions or by fetching live record details with Lightning Data Service ( getRecord ) to populate secondary fields instantly. Manually entering repetitive data slows down business users and increases data entry errors. Implementing smart autofill functionality provides a streamlined, desktop-grade experience. Depending on your use case, you can implement instant keyword-based auto-completion or automatic field population from linked Salesforce records.