Search filters are pre-made search strategies. They are developed by subject experts and are generally tested and validated. They may target research using a specific study design (e.g. randomised controlled trial) or topic (e.g. kidney disease) or some other feature of the research question (such as the age of participants). They can be copied and pasted into a database and combined with the rest of your search concepts. This saves time and effort, in both the creation of the search strategy and in reducing the number of records that you need to screen.
Study design search filters can be found at the following sites.
Subject search strategies can be found at: