The term “assault rifle” was introduced in 1944 to distinguish it from a “rifle”. Most infantry in WW2 were armed with bolt action rifles firing high power cartridges (exception: the US, which issued semiautomatic rifles as the standard infantry weapon.). The first so-called assault rifle (“sturmgewehr”) was developed by the Germans late in WW2.  After WW2, countries following the US lead from WW2 abandoned bolt action rifles and re-armed with semiautomatic rifles holding 10 or more rounds in detachable magazines. Many of these rifles had full automatic fire capability, but the high power rounds they fired made controlled, full automatic fire impossible.  By the 1960s, countries moved towards the adoption of lower power and/or smaller caliber cartridges that could be fired with some degree of control in full automatic mode from a rifle that weighted well under 10 pounds. The US adopted the AR 15 (M16), and the Eastern bloc adopted a successor of the AK47. These rifles are issued to all infantry, not just to elite troops. They are now the standard issue military rifle everywhere. They are capable of single shot fire, burst fire, and full automatic fire. They all have detachable magazines.  Civilian versions of these military rifles lack the capability for full-automatic or burst fire. Otherwise they are the same as the rifles used today by soldiers…. as are the bolt action rifles now used by many civilians identical in essential performance to the rifles used by most soldiers from 1890 to 1950. Ditto for the rifles in use by both soldiers and civilians in the 1790s when the 2nd Amendment was adopted.  The only feature of military “assault” rifles that has been denied to civilians is full automatic or burst fire. This was banned by the firearms act of 1934…long before any “assault rifle” existed.  What the gun control lobby calls an “assault rifle” is simply a military rifle that lacks the full automatic fire capability of military arms.
Among President Obama's proposals to change gun laws is a call for Congress to end the sale of certain semiautomatic rifles and high-capacity ammunition magazines. Here is a primer on the basic types of modern firearms.