〜たび（に）
Every time…, … againmachine translation
FormationVerb dictionary form + たび（に）／noun + の + たび（に）
〜たびに expresses "every time A happens, B happens along with it": この歌を聞くたびに、学生時代を思い出す (every time I hear this song, I remember my student days). Written in kanji it is 度. Verbs attach in the dictionary form; nouns attach with の: 旅行のたびに (every time I travel).
B is usually an emotion, a memory, or a discovery the speaker makes over and over — and it is precisely this "it's like this every time, here we go again" nuance that sets たびに apart from the conditional 〜と you learned at N4: 春になると花が咲く states a mechanical law of nature, while 会うたびに髪型が変わっている recounts a repeated experience with a touch of surprise.
Because it expresses repetition, たびに is not used for something that happens only once, and the second clause doesn't take commands or expressions of will. When B increases a step further with each occurrence of A, the sentence takes on an added "more and more" nuance: 会うたびに日本語が上手になっている.
Examples
この歌を聞くたびに、学生時代を思い出します。
Every time I hear this song, I remember my student days.
彼女は会うたびに、髪型が変わっている。
Every time I see her, her hairstyle is different.
旅行のたびに、その町の写真をたくさん撮ります。
Every time I travel, I take lots of photos of that city.