When this argument does not contain a slash, the shell will search for the file in all directories defined in the PATH environment variable.
Unlike normal commands which are also found in PATH, the file to source does not have to be executable.
[1] In several "extended" shells including bash,[3] zsh[4] and ksh,[5] one may specify parameters in a second argument.
Therefore, the dot command can be used for splitting a big script into smaller pieces, potentially enabling modular design.
[6] Frequently the "current context" is a terminal window into which the user is typing commands during an interactive session.