Looker automatically provides users with the ability to manipulate their queries by creating filters, which are based on dimensions and measures. While this simple method meets many use cases, it can’t enable every analytical need. Templated filters and Liquid parameters vastly expand the possible use cases you can support.
From a SQL perspective, dimensions and measures can only alter the outermost WHERE or HAVING clauses in your query. However, you might find that you want to let users manipulate other parts of the SQL. Adjusting part of a derived table, adjusting which database table gets queried, or creating multipurpose dimensions and filters are just some of the features you can enable with templated filters and Liquid parameters.
Templated filters and Liquid parameters make use of the Liquid templating language to insert user input into SQL queries. First, you use a LookML parameter to create a field for users to interact with. Next, you use a Liquid variable to inject the user input into SQL queries.
The Templated filters and Liquid parameters documentation page details the followings: