How does caching work? queries

[slick101]

I have been towards caching my website. The problem is im not sure if i grasp the total aspect of caching.

Lets say I have a user profile that people can comment( like facebook ). Now how do you go by caching that because users may leave comments or upload new pictures etc. Wont that page be cache already so you wont see any updates?

I have basically a template setup ( i use smarty ) and i have user pages. So my template file is always changing. Was this a bad approach? should i instead create their own template files? But still how do i go by caching when pages are always changing every second or so on so i can improve the optimization of results?

[dagon]

if its always changing, don't cache it, or only cache the parts that are not changing.

For the vast majority of sites there's little to be gained by caching. Webservers are fast, db's are fast, connections are fast. unless its a particularily busy site. it may be more trouble than its worth.