# Automatically excluding certain items

Sometimes there are files or folders which should be skipped over in a backup. The Rules tab allows you to specify rules which cause Synk to skip over files and folders which match a particular set of criteria.

The "Edit Rule" sheet appears when you either create a new rule by clicking on the "Add Rule" button or when you click the "Edit" button to change an existing rule.

Use "Description" field to define a name to help you remember what the rule does. This has no impact on the behavior of the rule, but is how the rule is shown in the main rule list.

There are three main options that determine the overall behavior of the rule: [Exclude/include] item if [any/all] of the following conditions are met on [either source/both sources].

- The exclude/include option determines what action is taken if the rule matches. Most of the time, you will want to use the exclude option as all items are included by default. However, if there are a few exceptions to a general exclusion rule, you can create an inclusion rule that is a higher priority than the exclusion rule so that those exceptions will be included.
- The any/all option determines whether all or any of the criteria you define must be matched in order for the rule to apply.
- The either source/both sources option determines whether each criterion must match the item in both Source A and Source B, or just one. Careful, if an item only exists in one source, no rules set to require matching both sources will be able to match it.

The criterion definition interface should be familiar to most users from other applications like the Finder and Mail. The first drop down controls which attribute of the item is tested, such as the filename, date created or modified, the label, or others. Click here for more information on criterion attributes.

The remainder of the criterion changes based upon which attribute you choose to test. To add another criterion, click the plus button next to any criterion. To remove a criterion, click the minus button next to that criterion.

Due to a bug in the Cocoa frameworks, international users should be careful with the date parsing in the date rules. Some localized date formats will not be properly read by the text field; however, the displayed date will be properly in your localized format.