Be careful in your selection. If you choose backticks or system( ), your script will not continue execution until the process call is complete. If that process takes too long, and this is a CGI process, the calling script could timeout, and return a 504 error to your browser.
This call executes a command and doesn't return. This, effectively, kills your script.
This call executes a command, and the calling script will wait for the command to execute before continuing. However, you can work around this by backgrounding the process:
system("perl some_process.pl &");
This call executes a command, then waits for the STDOUT output of the command, before continuing.