Create:
Insert new documents into a collection.

db.users.insertOne({
    name: "Alice",
    age: 28,
    interests: ["reading", "hiking"],
    address: { city: "Denver", state: "CO" }
});

Read:
Retrieve documents using queries.

// Find by a simple query
db.users.find({ name: "Alice" }).toArray();

// Find using projections to return specific fields
db.users.find({ age: { $gt: 25 } }, { name: 1, interests: 1 }).toArray();

Update:
Modify existing documents.

db.users.updateOne(
    { name: "Alice" },
    { $set: { "address.city": "Boulder" } }
);

Delete:
Remove documents from a collection.

db.users.deleteOne({ name: "Alice" });