〜ば、〜 (~ba, ~) — If ~, then ~

Grammar rule (व्याकरण नियम र परिभाषा)

A conditional form plus a second clause says "if A happens, B happens". A is the condition, B is the result. It carries the feeling that once the condition is met the result follows naturally, so it is common in advice, rules and facts of nature — 押せば、開きます。安ければ、買います。Remember one big rule: if both halves have the same subject and the first half is an action verb, you cannot put a request, an order, an invitation or a wish after it. ✗ 東京へ 行けば、電話して ください。In that case use たら — ○ 東京へ 行ったら、電話して ください。But if the first half is a state (い-adjective, な-adjective, ない, or a verb like ある・いる・わかる) a request is fine — ○ 分からなければ、聞いて ください。It is also fine when the subjects differ — ○ 田中さんが 行けば、私も 行きます。 Which to pick? Use ば when you want to stress that the result only follows if the condition is met. Use たら when you need a request after it.