Elastic Compute Cloud (EC2) is a core service provided by Amazon Web Services (AWS) that offers scalable computing capacity in the cloud. With EC2, users can create and configure virtual machines (instances) to run various applications, ranging from simple web servers to complex database clusters.

EC2 provides a wide range of instance types with varying CPU, memory, and networking capabilities to suit different workload requirements. These instances can be quickly launched, configured, and scaled, offering the flexibility to increase or decrease resources as needed.

Additionally, EC2 offers features such as security groups for network security, elastic IP addresses for static addressing, load balancers for traffic distribution, and Auto Scaling to automatically adjust the number of instances based on current demand. Overall, EC2 enables businesses to utilize computing resources on-demand in the cloud, facilitating cost optimization and scalability.