Verbs of motion (for David http://www.italki.com/entry/338177)
Идти = to go on foot
Ехать = to go in a vehicle
Unidirectional vs Multidirectional:
Идти — one-way trip with no implication of returning ----
Ходить — multi-directional counterpart of Идти, with implication of returning (and repeating)
Ехать — one-way trip in a vehicle with no implication of returning ----
Ездить — multi-directional counterpart of ехать, with implication of returning and repeating