Freelander 1 What is the egr

Hi all,
forgive my ignorance as I am a new Freelander owner. Can someone please tell me what the egr is and what is it's function. I have browsed many threads regarding this valve and notice some owners clean it and others blank it off and that leaves me confused. Please help

exhaust gas recirculation.

it returns some exhaust gas, oil, coke etc into the inlet, clogging up the inlet system. remove or blank off.

What he said

EGR reduces oxygenated air at certain times to reduce combustion temperatures and so reduce Nox production. When EGR is in operation the ECU modulates the EGR control valve which supplies a vacuum to the EGR valve to open it. Exhaust gas is then ingested by the engine to reduce combustible air. The reduction in airflow through the MAF sensor tells the ECU how much exhaust gas is being ingested. The ECU then further modulates the EGR valve to maintain a combustible air content subject to throttle and power level required, to cleanly burn the fuel needed to satisfy that throttle/power demand..

Thank you very much for the information. I can see that I am in the company of very knowledgeable Guys