Welcome back and congratulations on making it this far! So far in this course, you've become familiar with a range of powerful MongoDB operations, including updateOne, updateMany, and various basic update operators. You've also explored operations like replaceOne and the upsert option. Today's lesson focuses on working with array fields in MongoDB. You'll learn how to change all array items using $[], update array elements by index, update the first matching array element using $, and modify all items that match a given condition using $[<identifier>].

Here is a brief overview of the array update operators available in MongoDB for manipulating array fields:

• $: Used to update the first element that matches the query condition.
• $[]: Used to update all elements in an array for documents that match the query condition.
• $[<identifier>]: Used to update all array elements that match the condition specified in arrayFilters for documents that match the query condition.