I am trying to understand the precise (objective) history of either the Department of Homeland Security (DHS) or Immigration and Customs Enforcement (ICE) practice of separating children (minors) of illegal immigrants from their parents when the parents are arrested for deportation. Meaning: John and Jane Doe and their (say) 5-year old son Jake are found living here in the United States illegally; ICE comes and arrests them and intends to deport them back to their country of origin, and John/Jane are separated from Jake for some duration of time.

From what I can tell, the present administration was made aware of this practice several years ago, and in 2018, signed something (executive order perhaps?) that put an end to this practice altogether.

However I have also heard claims that this practice has been going on for decades and was not something that the present administration began doing; merely something it inherited.

So I am trying to determine: what this practice/policy is or was (is there a name for it?), what the policy actually was and how it worked, when it began/formed and what was signed in 2018 to "end" it?