You can define characters or words that will be ignored when the user performs a product search.
This is very useful when you have dashes in SKU numbers or other data.
By default two characters are set to be ignored: – and _
When your product SKU number is 01_ROS_2017 normally the user must insert the dashes to find this particular product. You you have configured the search to ignore the dashes you will be able to find this product with 01 ROS 2017 (the same but without the dashes).