# Train a Binary Category

You can use the `BinaryCatTrain` action to train a binary category. Unlike normal categories, which have only positive training, binary categories can have both positive and negative training.

If the binary category has existing training, `BinaryCatTrain` adds the new training to it. If you want to replace the training for a binary category, you must first use the `BinaryCatDeleteTraining` action to delete the existing training. For example:

    http://12.3.4.56:9020/action=BinaryCatTrain&Name=spam_binarycat&PositiveDocID=123,456&NegativeDocID=789,890

This action uses port `9020` to instruct the IDOL Category component, which is located on a machine with the IP address `12.3.4.56`, to train the binary category named `spam_binarycat`. It uses the documents with IDs `123` and `456` for positive training, and the documents with IDs `789` and `890` for negative training.

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