EC2 — Virtual Servers in the Cloud

Amazon EC2 (Elastic Compute Cloud) provides resizable virtual servers (instances) in the cloud. It's the most foundational AWS compute service.

EC2 instance types (families):

General Purpose (T, M) — balanced CPU/RAM; web servers, small databases

Compute Optimized (C) — high CPU; batch processing, gaming, ML inference

Memory Optimized (R, X) — large RAM; in-memory databases, real-time analytics

Storage Optimized (I, D) — high IOPS; data warehousing, Hadoop

Accelerated Computing (P, G) — GPU; ML training, video encoding

EC2 pricing models:

On-Demand — pay per second/hour; no commitment; most expensive; for unpredictable workloads

Reserved Instances — 1 or 3-year commitment; up to 75% discount; for steady-state workloads

Spot Instances — unused capacity; up to 90% off; can be interrupted; for fault-tolerant batch jobs

Dedicated Hosts — physical server dedicated to you; for compliance/licensing

Savings Plans — flexible commitment to compute usage; up to 72% off

Reference:

Wikipedia: Amazon EC2

https://en.wikipedia.org/wiki/Amazon_Elastic_Compute_Cloud