Far Right - Far left what do they mean

In the French Assembly of 1789, the radicals sat in the left in a group, and the conservatives sat on the right. Since nearly all future revolutions were patterned after the French Revolution, the name stuck.

As far as what do these things stand for, especially far right or far left, in the US, they have a fluid meaning, just like their co-words liberal and conservative, and many politicians are conservative in some areas and liberal in others.