The main problem comes from way back, when the main language in computing was English. The ASCII characters were given numbers from 1 to 128 a-z, A-Z, 0-9 and punctuation. That is fine for the English language but pretty much every other language out there has characters that don't fit in there. To address this, we have UTF-8, which can store extra characters as multiple-bits and is backwards compatible with ASCII.
To make your CodeIgniter application play nicely with UTF-8 you have a few things to think about.
CodeIgniter by default is set to use UTF-8 for much of its internal functionality, so just make sure the charset is set to UTF-8 in your application/config/config.php file.
$config['charset'] = "UTF-8";
Setting UTF-8 as meta tag in the header is not sufficient, if you are working European characters. For example, to display Swedish characters å,ä,ö in the website.
<meta http-equiv="content-type" content="text/html; charset="utf-8">
You will get following rendered text in your browser.
Hej! Det h�r meddelandet �r p� Svenska.(default)
You have to save file as UTF-8 as well. But using the correct doctype and encoding for the document helps crippled browsers.
If you are using coda as text editor, Check at Text/Encoding to know which encoding are you using while saving the file.
If you save the file with correct encoding i.e Unicode UTF-8 , then you will get the correct result:
Hej. Det här meddelandet är på Svenska.
Hope this will help who is having problem.
Ref: http://philsturgeon.co.uk/blog/2009/08/utf-8-support-for-codeigniter and http://ellislab.com/forums/viewthread/128608/