What is the meaning of ideal gas?
An ideal is a theoretical model of a gas which perfectly obeys all the gas laws.
There are two most basic features of an ideal gas which distinguishes it from the real gases -
1) The molecules of an ideal gas occupy negligible volume.
2) The ideal gas molecules are weakly interacting, i.e. the molecules only interact via collisions and do not exert intermolecular forces.
Real gases tend to the ideal gas behavior for low pressures and high volumes where these two distinguishing factors become insignificant.