SPF is short for Sun Protection Factor. It is the number printed on sunscreen — SPF 30, SPF 50 — telling you how much the cream protects your skin from burning in the sun. A bigger number means more protection.

SPFSPF is short for是...的縮寫 Sun Protection FactorSun Protection Factor（防曬係數）。It is the number printed on sunscreen它是印在防曬乳上的數字 — SPF 30, SPF 50像SPF 30、SPF 50 — telling you how much the cream protects your skin from burning in the sun告訴你這款乳液能讓你的皮膚多不容易被太陽曬傷。A bigger number數字越大 means more protection代表防護力越強。

You say the three letters separately: ess-pee-eff.

You say the three letters separately這三個字母要分開唸: ess-pee-effess-pee-eff。

In real speech people use it as a noun on its own ("What SPF is that?", "I need a higher SPF") and also right before the number as a kind of label ("Put on SPF 50"). Many people now say SPF when they simply mean the sunscreen itself — "Did you bring the SPF?" — which dictionaries do not always show, but you will hear it, especially from younger speakers.

In real speech在實際說話中 people use it as a noun on its own人們會單獨把它當名詞用 ("What SPF is that?", "I need a higher SPF")('What SPF is that?'、'I need a higher SPF') and also right before the number as a kind of label也會直接放在數字前面當標籤 ("Put on SPF 50")('Put on SPF 50'). Many people now say SPF現在很多人用SPF when they simply mean the sunscreen itself單純指防曬乳本身 — "Did you bring the SPF?"'Did you bring the SPF?' — which dictionaries do not always show字典不一定會收錄這種用法, but you will hear it但你會聽到, especially from younger speakers尤其是年輕人。

A thing worth telling students: the number is about burning from one kind of sun ray only, which is why bottles add words like broad spectrum or, in Taiwan and Japan, PA+++. And a very high number is not as different as it looks — SPF 50 is only a little better than SPF 30, not almost twice as good.

A thing worth telling students值得告訴學生的一件事: the number is about burning from one kind of sun ray only這個數字只針對一種太陽光造成的曬傷, which is why bottles add words like broad spectrum這也是為什麼瓶身上會加上broad spectrum這類字, or, in Taiwan and Japan, PA+++或者在台灣和日本會標PA+++. And a very high number is not as different as it looks而數字很高其實沒有看起來差那麼多 — SPF 50 is only a little better than SPF 30SPF 50只比SPF 30好一點點, not almost twice as good不是幾乎兩倍好。

Careful writers keep it in capitals with no full stops.

Careful writers謹慎的寫作者 keep it in capitals with no full stops會把它全部大寫，中間不加句點。