Clientside:
Scripts are placed inside a <script> tag in the page. Visitors are able to see the scripts in the source code of the page. The scripts are run on your computer.
Advantages:
- Can do more, e.g. make items move.
- Can perform actions without having to reload the page first.
- Can be used with HTML tags. (e.g. onLoad, OnMouseOver)
- Are used to make rollover buttons, which are an important part of many websites.
Disadvantages:
- Scripts are interpreted at the visitors browser, if their browser is out-of-date the website will not display properly
- Not secure, anyone can look at the code in the page source
- Can slow down old computers
- Some browsers disable active content, such as clientside scripts and tell the user they may be harmful
Some common uses:
- Button rollover effects
- Cursor trails
- Form verification
- Creating cookies
Serverside:
Scripts are placed inside a <? tag in the page. Visitors are not able to see the scripts. The scripts are run at the server, then the result is sent to your computer.
Advantages:
- More secure, visitors aren't able to view scripts
- All scripts are performed at the server, it will work with any browser
- You are able to include external files, to save coding
- You can combine it with programs such as MySQL
Disadvantages:
- Scripts can only be performed when the page loads/reloads
- When moving sites, some code may have to be modified, depending on the configuration and version of PHP
- In most languages, variables must be preceeded with a $ sign
- All lines must end in a semicolon (
Some common uses:
- User management
- File includes
- Database communication
- Finding $_GET variables (e.g. index.php?variable=value)
I hope that helped you decide which is the best for you! So you're less
and more 
!
.
