Elastic Compute Cloud (EC2) is a web service provided by Amazon Web Services (AWS) that allows users to rent virtual computing resources in the cloud. It is one of the fundamental components of AWS and offers scalable computing capacity in the form of virtual servers, known as instances.

Key features of Amazon EC2:

1. Scalability: EC2 enables users to easily scale up or down their computing resources based on demand. This is particularly useful for applications with varying workloads or for handling unexpected spikes in traffic.

2. Instance Types: EC2 provides a variety of instance types optimized for different workloads, such as general-purpose, memory-intensive, compute-optimized, and GPU-powered instances. Users can choose the most suitable instance type for their specific application requirements.

3. Operating System Support: EC2 instances support a wide range of operating systems, including various Linux distributions, Windows Server, and others, giving users flexibility in choosing their preferred operating environment.

4. Pay-as-You-Go Pricing: EC2 operates on a pay-as-you-go model, where users only pay for the computing resources they consume. This allows for cost-effective usage, as instances can be easily started or stopped as needed.

5. Security and Networking: EC2 provides several security features, such as Virtual Private Cloud (VPC) for creating isolated network environments, security groups for firewall configuration, and Identity and Access Management (IAM) for access control.

6. Data Storage Options: EC2 instances can be attached to various storage options, including Elastic Block Store (EBS) for persistent block storage, and Amazon S3 for object storage, among others.

7. Auto Scaling: EC2 can be integrated with Auto Scaling, which automatically adjusts the number of instances based on predefined conditions, ensuring that the application can handle changes in demand without manual intervention.

8. Load Balancing: Amazon EC2 instances can be easily deployed in conjunction with Elastic Load Balancing (ELB), which distributes incoming application traffic across multiple instances, ensuring better availability and fault tolerance.

EC2 is widely used by businesses and developers to host web applications, run batch processing, perform data analysis, and handle various other computing tasks in a flexible and cost-efficient manner. It has become a cornerstone service for cloud computing, enabling users to easily deploy and manage virtual servers without the need for hardware investment and maintenance.