> For the complete documentation index, see [llms.txt](https://blog.telegram.lvivcenter.org/tg-research/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blog.telegram.lvivcenter.org/tg-research/filters/filters-basics.md). # Basic Information about Filters {% embed url="" fullWidth="true" %} Before we move on to filters, we suggest you familiarize yourself with the main features of working with them: * A system of logical operators `OR` and `AND` is applied in each filter. By default, the `AND` operator is in effect, combining all selected search queries. For example, with the filters "Country" > "Ukraine" `AND` "Poland" enabled, the results will display messages that mention both countries. By changing the operator from `AND` to `OR` in the lower right corner of the filter, the results will display messages that mention one `or` more countries.
* All selected filters are displayed at the top of the search results. This allows you to see which filters are active and easily disable them.
* Next to each item in the filter panel, the number of messages corresponding to that item is displayed. For example, this could be the number of messages with a specific hashtag or those published by a particular author. These numeric indicators may change if the search parameters are adjusted.
* Since the list in some filters can be too long, each has a button. You can view the entire list using this button and find the items you need by name. The display order can be sorted alphabetically (thebutton) or by the number of messages (thebutton).