# What's the purpose of tunegrid in the caret package?

I am deciding the parameters for a random forest classification model. I am using the caret package and read, here, about the tuning grid. My understanding is that it helps determine the best values for the tuning parameters, like mtry and n.trees.

Isn't that redundant to trControl? As I understand it, if I set trControl to trainControl(method = "repeatedcv", number = 10, repeats = 3), then it will re-run the model three times with ten-fold cross validation to find the best values for the tuning parameters.

If that's true, then what purpose does tunegrid serve?