Amazon Simple Storage Service (Amazon S3)

An object storage service that offers industry-leading scalability, data availability, security, and performance.
Customers of all sizes and industries can use Amazon S3 to store and protect any amount of data for a range of use cases, such as data lakes, websites, mobile applications, backup and restore, archive, enterprise applications, IoT devices, and big data analytics.
Amazon S3 provides management features so that you can optimize, organize, and configure access to your data to meet your specific business, organizational, and compliance requirements.

Features of Amazon S3

Storage classes
Storage management - Lifecycle, Object Lock, Replication, Batch Operations
Access management and security - Block Public Access, Identity and Access Management (IAM), Bucket policies, access points, control lusts (ACLs), Object Ownership, IAM Access Analyzer
Data processing - Object Lambda, Event notifications (Amazon SNS, Amazon SQS, AWS Lambda)
Storage logging and monitoring - Automated, Manual monitoring tools
Analytics and insights - Storage lens, Class Analysis, Inventory with Inventory reports
Strong consistency

How Amazon S3 works

Amazon S3 is an object storage service that stores data as object, hierarchical data, or tabular data within buckets.
An object is a file and any metadata that describes the file.
A bucket is a container for objects.

Create a bucket and specify a bucket name and AWS Region.
Upload data to that bucket as objects in Amazon S3. - Each object has a key (or key name), which is unique identifier for the object within the bucket.

Refference

docs.aws.amazon.com - What is Amazon S3?