# Training an ID Tool

An ID tool supports an optional training phase to establish the values for parameters the tool will use to repeatedly decode 2D symbols, such as the size of the symbol grid, the 2D symbology, and the error checking and correction (ECC) method the symbol uses to verify the accuracy of the data it contains.

Training an ID tool can improve its performance when all the symbols you need to decode share the same qualities, while not training an ID tool allows it to decode a wider variety of 2D symbols.

Cognex recommends you train the tool when the 2D symbols your application needs to decode all share the same characteristics. Do not train an ID tool, however, if the 2D symbols can vary in parameters such as grid size or polarity. Not training the tool allows it to consider all possible settings as it executes.