파일 크기 refers to the amount of digital space a file occupies on a storage device, such as a hard drive or USB flash drive. It is usually measured in bytes, with larger files measured in kilobytes (KB), megabytes (MB), gigabytes (GB), or terabytes (TB). Understanding file size is important for managing storage and ensuring that devices have enough space for new files. When downloading or uploading files, knowing the file size helps users estimate the time required for the transfer. For example, larger files like videos or high-resolution images typically take longer to upload or download compared to smaller files like text documents. Managing file sizes can also help optimize performance on devices like computers and smartphones.