Can variables be shared across sessions?

Hi All

Another newbie question. I have a small website working via php and all is
fine, but I wanted to add some new features and was wondering if php allows
for variables to be seen by multiple sessions, ie a user viewing the web
site on one machine can see variables created by another users session. Is
that what $_SERVER[] is for, or am I going to be better of creating a single
entry table in mySQL that has a field for each global variable?

Many thanks


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