A well constructed systematic search is a core element of a systematic review. The aim is to identify and collect all relevant literature (evidence) to answer a clearly formulated qestion.
A systematic search requires a predefined and structured design which is tested through exploratory searches. Each search term is carefully considered, you consider your choice of inclusion and exclusion criteria, use of search tactics and different search methods and evaluate the results of the search throughout the search process.
By searching systematically, you have a greater chance of decreasing bias and a greater chance of increasing the validity of the search and identify gaps in existing knowledge that your research could fill. Consequently, you reduce the risk of replicating research that has already been done and increase the originality of your own work.