Upload

In computing, upload is the act of transferring data from a local device to a remote system. It contrasts with download, which copies data from a remote system to the local device. Uploads are fundamental to user-generated content, file sharing, and data submission workflows.

Common methods include web forms that post files to a server, FTP and SFTP transfers, and programmatic APIs that accept multipart or streaming data. Web-based uploads often use HTTP POST requests or multipart/form-data encoding; mobile and desktop apps may implement resumable uploads to recover from interruptions. Large files are frequently divided into chunks to support retries and progress tracking.

After transfer, the storage location may be a file system, object storage, or a database, with metadata such as name, size, type, and timestamps. Uploads are integral to cloud storage services, content platforms, and software distribution, enabling users to share documents, images, videos, and other assets.

Security and reliability concerns include authentication and authorization, input validation, size limits, and antivirus scanning. Transfers should use encryption in transit (for example, TLS); integrity checks like checksums or digital signatures verify that uploaded data is complete and unaltered. Resumable and chunked uploads improve resilience over unreliable networks.