For some reason, when I make a text file on OS X, it's always at least 4kB, unless it's blank. Why is this? Could there be 4,000 bytes of metadata about 1 byte of plain text?
Why are text files 4kB?
filesystems;disk usage
The block size of the file system must be 4 kB.  When data is written to a file that is contained in a file system the operating system must allocate blocks of storage to contain the data that will be written to the file.  Typically, when a file system is created the storage contained in that file system is segmented into blocks of a fixed size.  This Wikipedia article briefly explains this process.The underlying block size of the file system for this file must have a 4K byte block size.  This file is using 1 4K block and only one byte within that block contains actual data.