Building applications without managing servers, also known as serverless computing, is a cloud computing model where the cloud provider manages the infrastructure and dynamically allocates resources as needed.

*Key Characteristics:*

1. *No server management*: The cloud provider manages the servers, including provisioning, patching, and scaling.

2. *Event-driven*: Applications are triggered by events, such as HTTP requests, database updates, or message queue events.

3. *Scalability*: Resources are dynamically allocated and scaled as needed, eliminating the need for manual scaling.

4. *Pay-per-use*: Pricing is based on the actual resources consumed, rather than pre-provisioned resources.

*Benefits:*

1. *Reduced administrative burden*: No server management means less administrative work.

2. *Increased scalability*: Resources are dynamically allocated, ensuring applications can scale quickly.

3. *Cost savings*: Pay-per-use pricing reduces costs, as resources are only consumed when needed.

4. *Faster deployment*: Serverless applications can be deployed quickly, without the need for server provisioning.

*Challenges:*

1. *Vendor lock-in*: Serverless applications may be tightly coupled to a specific cloud provider.

2. *Debugging and monitoring*: Debugging and monitoring serverless applications can be more complex.

3. *Cold start*: Serverless functions may experience a "cold start" delay when invoked after a period of inactivity.

*Use cases:*

1. *Real-time data processing*: Serverless computing is well-suited for real-time data processing, such as IoT sensor data or social media feeds.

2. *Web applications*: Serverless computing can be used to build scalable web applications, such as APIs or web servers.

3. *Machine learning*: Serverless computing can be used to deploy machine learning models, reducing the need for manual infrastructure management.