Analysis
Filter
Also called view filter.
Filter is a rule that includes or excludes hits, sessions, or rows from what a report shows. Some filters change the stored data; others only change the view.
How it is measured
A filter has a field, an operator, and a value, such as hostname equals the shop domain. A permanent filter changes what is stored from then on. A report filter narrows what you see and can be removed.
Test a new filter on a copy before you apply it. Compare counts with and without it for a known day and make sure the difference matches what you meant to exclude.
Worked example
A co-working space sees 1,900 daily sessions, of which about 300 come from its own office network. An internal-traffic rule removes hits from one IP range.
A week later the owner notices that the booking page count dropped by half. The rule had a typo that matched a wider range and also dropped a partner's building. Reversing it needed a backup property, since data already excluded could not be recovered.
How it differs
A filter removes or keeps data by rule. A segment is a saved slice of what remains and can be switched off in a report. Only the filter can destroy data.
Common errors
Applying a permanent filter without testing. Using a case-sensitive match. Excluding by an IP that changes. Stacking filters in the wrong order. Forgetting to document who set a filter.
In practice
List every active filter on your property with its owner and date. Keep one unfiltered copy so mistakes can be undone. Use segments for exploration and filters only for clear exclusions.