What Open System Interconnect layer is closest to the end user?

The Application layer is indeed the closest layer to the end user in the Open Systems Interconnection (OSI) model. This layer is where users interact directly with the software applications that facilitate communication over a network. It is responsible for providing network services directly to the user's applications, which include web browsers, email clients, and file transfer programs.

At this layer, protocols such as HTTP, FTP, and SMTP operate, enabling users to perform various tasks like accessing web pages, sending emails, and transferring files. The close proximity to the user's experience makes the Application layer essential for relating network operations to user needs and preferences.

Other layers, such as Session, Presentation, and Transport, play important roles in managing network communications but do not directly interface with users. The Session layer helps manage sessions between computers, the Presentation layer formats and encrypts data, and the Transport layer ensures reliable data transfer across the network. However, they do so in a more backend capacity, abstracted away from the end user's direct interaction.