What is AWS Lambda?
AWS Lambda is a serverless compute service. That means:

You don’t need to create or manage any server.

You just write your code.

AWS will run your code only when it’s needed (event-based).

You pay only for the compute time you use.

💡 Real-World Example: Save Product Data to DynamoDB
Let’s say you are building a small inventory system where each time someone adds a product, you want to store it in DynamoDB.

Here’s how we’ll do it using Lambda:

🛠️ Step-by-Step Guide
✅ Step 1: Create a DynamoDB Table
Go to AWS Console → DynamoDB → Create Table:

Table name: ProductsTable

Partition key: product_id (String)

✅ Step 2: Create a Lambda Function
In AWS Console:

Go to Lambda

Click Create Function

Select Author from Scratch

Runtime: Python 3.12 (or latest)

Name: AddProductFunction

Now paste the following code:

python
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import json
import boto3

DynamoDB connection

dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('ProductsTable')

def lambda_handler(event, context):
# Read data from the incoming event
product = json.loads(event['body'])

# Insert into DynamoDB
table.put_item(Item={
    'product_id': product['id'],
    'name': product['name'],
    'category': product['category']
})

return {
    'statusCode': 200,
    'body': json.dumps('Product added successfully!')
}

✅ Step 3: Test the Lambda
Click on Test and use this sample event:

json
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{
"body": "{\"id\": \"101\", \"name\": \"Pen\", \"category\": \"Stationery\"}"
}
✅ After running it, check your DynamoDB table — you’ll see the new product saved!

🔄 Behind the Scenes – What Just Happened?
The event['body'] contains the product details in JSON.

Lambda reads the body, parses it.

Uses boto3 (AWS SDK) to connect to DynamoDB.

Saves the product using put_item.

Returns success response.

🌐 Where Can This Be Used?
Inventory Management

User Registrations

IoT Data Storage

Image Metadata Saving (when combined with S3)

🎯 Final Thoughts
AWS Lambda allows developers to focus purely on logic, not infrastructure. Whether you're building a quick backend for a hackathon or a full microservice, Lambda scales automatically, handles failures, and reduces cost.