libphp4.so vs libphp4.a
 

good day to all.

can anyone tell me whats the difference between this file:
a. libphp4.so (installed on default within php)
b. libphp4.a (find in other linux apache+php+postgres installation tutorial)
libphp4.a was generated on configuration using:
--activate-module=src/modules/php4/libphp4.a

im running slackware 10. and i want to re install my apache+php..
apache and php are included in my distro installation.

please post elaborated explanation coz i really want to understand what this files are and their difference..

thanks in advance..