Prefixes change the direction of motion
Russian builds an entire set of motion verbs by attaching prefixes to идти / ехать. Each prefix specifies HOW the motion happens — into, out of, across, up to, away. With a prefix, the unidirectional verb becomes perfective (a single completed trip).
по- = setting off
пойти / поехать = to set off, to head out (one trip). Я пошёл в школу = I went / set off for school. Завтра мы поедем в Москву = Tomorrow we'll head to Moscow. This is the most common way to talk about a one-time future trip.
при- = arrival
прийти / приехать = to arrive. Анна пришла домой = Anna came home. Иван приехал из Москвы = Ivan arrived from Moscow. Прийти is irregular — note the 'й'.
у- = leaving / going away
уйти / уехать = to leave (and not come right back). Папа ушёл на работу = Dad left for work. Они уехали в Россию = They've left for Russia.
вы- = going out (out from somewhere)
выйти / выехать = to go out / step out. Я выйду на минуту = I'll step out for a minute. Машина выехала из города = The car drove out of the city.
Aspect with prefixed motion
Prefixed unidirectional → perfective (one trip): пошёл, пришёл, ушёл. For the imperfective version (habitual, repeated leaving/arriving), Russian builds it from the multidirectional ходить/ездить with the same prefix: приходить, уходить, etc. прийти (pf) / приходить (impf) — to arrive. уйти (pf) / уходить (impf) — to leave. Use perfective for a single event ('she arrived'), imperfective for habit ('she comes here often').
