You may occasionally see a Publish button in your Admin Area navigation bar to the right of the Settings menu.
This usually means you have made changes in one or more sections under the Design menu that are not yet reflected on your storefront. By default, all stores are set to immediately publish changes automatically. In most cases, the button appears only if you have manually turned off immediate publishing.
To turned it back on, go to Settings > Config Variables, select the Enable Immediate Publish check box, and press Save. If you would like to disable immediate publishing, clear the check box and save. You can then choose when to make changes live by pressing the Publish button at your convenience.
If the Publish button displays and the Enable Immediate Publish check box is selected, you can safely ignore the Publish button; your changes are publishing automatically.