Magento’s cache management system is an easy way to improve the performance of your site. Whenever a cache needs to be refreshed, a notice appears at the top of the workspace to guide you through the process. Follow the link to Cache Management, and refresh the invalid caches.
To access the cache management screen, you can also use the link in the admin panel menu: System > Cache Management.
Always refresh the cache after making changes in the configuration of your Magento/themes/extensions or after making any custom changes in the files.
http://docs.magento.com/m2/ce/user_guide/system/cache-management.html
Flush cache
Go to System > Cache Management. Click the following buttons to completely clear the store cache:
- Flush Magento Cache
- Flush Cache Storage
Disable cache
Go to System > Cache Management. Click Select All link, select Disable in Actions field and click Submit button.
Enable cache
Go to System > Cache Management. Click Select All link, select Enable in Actions field and click Submit button.
Refresh cache
If the cache is enabled, after each configuration change, extension installation, upgrade or uninstallation always refresh the cache. Go to System > Cache Management. Click Select All link, select Refresh in Actions field and click Submit button.