Lisp provides various facilities for input/output (I/O) operations to interact with the user and external devices. Here's an overview of how Lisp handles I/O :

1. Standard I/O Streams :
   * Lisp provides three standard I/O streams: `*standard-input*`, `*standard-output*`, and `*error-output*`. These streams are associated with the standard input, output, and error channels, respectively. They are used by default for I/O operations unless explicitly specified.

2. Reading Input :
   * The `read` function is used to read input from a stream. It reads and returns the next Lisp object from the specified input stream. By default, `read` reads from `*standard-input*`. Common Lisp also provides the `read-line` function to read a line of text as a string.

3. Writing Output :
   Lisp provides several functions for writing output to a stream:
   * `print` and `prin1` functions convert Lisp objects to their printed representation and write them to a stream.
   * `princ` function writes the external representation of an object to a stream.
   * `format` function provides more control over formatting and allows the construction of complex output.

4. Output Formatting :
   * Lisp provides formatting directives and control strings in the `format` function to control the formatting of output. This includes specifying field widths, precision, alignment, and other formatting options. 5. File I/O :
   * Lisp supports file I/O operations for reading and writing files. Common Lisp provides functions like `open`, `close`, `read-line`, `write-line`, `read-byte`, and `write-byte` for file handling. These functions allow you to open files, read and write data, and close files when finished.

6. Standard Error Output :
   * Error messages and other diagnostic information can be written to `*error-output*` using functions like `format` or `write-line`. By default, `*error-output*` is associated with the standard error channel.

7. Terminal Interaction :
   * Lisp provides functions like `read`, `read-char`, `write-char`, and `terpri` for interacting with the user on the terminal. These functions allow reading characters, writing characters, and moving to a new line.

8. Stream Handling :
   * Lisp provides functions and macros for stream handling, including querying stream properties, flushing output streams, positioning streams, and handling end-of-file conditions.