once you write an html fileyou need to put it somewhere web browser can reference it if you are using the locally running python web server described earlierthis becomes trivialuse url of the form and the web server script by default serves pages and scripts from the directory in which it is run on other serversurls may be more complex like all html filestutor html must be stored in directory on the server machinefrom which the resident web server program allows browsers to fetch pages for exampleon the server used for the second edition of this bookthe page' file must be stored in or below the public_html directory of my personal home directory--that issomewhere in the directory tree rooted at /home/lutz/public_html the complete unix pathname of this file on the server is/home/lutz/public_html/tutor html this path is different from its pp \internet\web location in the book' examples distributionas given in the example file listing' title when referencing this file on the clientthoughyou must specify its internet addresssometimes called urlinstead of directory path name the following url was used to load the remote page from the serverthe remote server maps this url to the unix pathname automaticallyin much the same way that the server script for our locally-running server in generalurl strings like the one just listed are composed as the concatenation of multiple partsprotocol namehttp the protocol part of this url tells the browser to communicate with the http ( webserver program on the server machineusing the http message protocol urls used in browsers can also name different protocols--for exampleftp:/to reference file managed by the ftp protocol and serverfile:/to reference file on the local machinetelnet to start telnet client sessionand so on server machine name and portstarship python net url also names the target server machine' domain name or internet protocol (ipaddress following the protocol type herewe list the domain name of the server machine where the examples are installedthe machine name listed is used to open socket to talk to the server as usuala machine name of localhost (or the equivalent ip address here means the server is running on the same machine as the client optionallythis part of the url may also explicitly give the socket port on which the server is listening for connectionsfollowing colon ( starship python net or : for httpthe socket is usually connected to port number climbing the cgi learning curve