Magento's System Requirements
Supported Operating Systems:
Supported Web Servers:
- Apache 1.3.x
- Apache 2.0.x
- Apache 2.2.x
- Nginx (starting from Magento 1.7 Community and 1.12 Enterprise versions)
Supported Browsers:
- Microsoft Internet Explorer 7 and above
- Mozilla Firefox 3.5 and above
- Apple Safari 5 and above on Mac only
- Google Chrome 7 and above
- Adobe Flash browser plug-in should be installed
PHP Compatibility:
- 5.2.13 - 5.3.15
- Required extensions:
- PDO_MySQL
- simplexml
- mcrypt
- hash
- GD
- DOM
- iconv
- curl
- SOAP (if Webservices API is to be used)
- Safe_mode off
- Memory_limit no less than 256Mb (preferably 512)
MySQL:
- 4.1.20 or newer
- InnoDB storage engine
SSL:
- If HTTPS is used to work in the admin, SSL certificate should be valid. Self-signed SSL certificates are not supported
Server - hosting - setup:
- Ability to run scheduled jobs (crontab) with PHP 5
- Ability to override options in .htaccess files
And here is How do I know if my server is compatible with Magento?