Assalam ALikum,
How are you all?
Well, I have a book that has been saved in a .cgi format and I wish that you can tell me how can I open and read it.

Thank you for your time,

Werner

.cgi ? This is the CGI scripts extension!!
try running
file <name of file>
and paste the output ;-)

Did u save it from a web site?
if so just rename it .html