The Slaves That Time Forgot
For some reason, history likes to call these Irish slaves as 'indentured servants'. As if they were somehow considered better than African slaves. This can be considered an attempt at whitewashing the history of the Irish slave trade.
There does exist indentured servitude where two parties sign a contract for a limited amount of time. This is not what happened to the Irish from 1625 onward. They were sold as slaves, pure and simple.
In reality, they were considered by some to be even lower than the blacks. African slaves were still relatively new, and were expensive to transport such a long distance (50 sterling in the late 1600's). Irish slaves on the other hand, were relatively cheap in comparison (5 sterling).