自: from, since (formal)
【四13】介词 / prepositions
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
自 is the written counterpart of 从: "from, since". It goes before the verb and introduces either the place of origin (自北京出发, 来自中国) or the starting point in time (自古以来, 自去年起).
With 以来 it forms the familiar 自……以来 ("ever since…"): 自去年以来，我一直住在杭州. On its own before a time word, 自 belongs to announcements, reports and speeches; in conversation people say 从.
自 does not introduce a person: to borrow from a friend you say 向朋友借 or 从朋友那儿借. 来自 is the neat way to say "come from"; in conversation 他是从西班牙来的 is just as common.
Examples
他来自西班牙，现在住在杭州。
Tā láizì Xībānyá, xiànzài zhù zài Hángzhōu.He comes from Spain and now lives in Hangzhou.
我们的航班准时自北京出发。
Wǒmen de hángbān zhǔnshí zì Běijīng chūfā.Our flight left Beijing on time.
自古以来，中国人就喜欢喝茶。
Zì gǔ yǐlái, Zhōngguórén jiù xǐhuan hē chá.Since ancient times, the Chinese have loved drinking tea.
自去年以来，来这里参观的游客越来越多。
Zì qùnián yǐlái, lái zhèlǐ cānguān de yóukè yuè lái yuè duō.Since last year, more and more tourists have come to visit.
自下个月起，商店每天早上九点开门。
Zì xià ge yuè qǐ, shāngdiàn měi tiān zǎoshang jiǔ diǎn kāimén.From next month, the shop will open at nine every morning.
Common mistakes
✗ 他自朋友借了一本书 → ✓ 他从朋友那儿借了一本书 (自 does not introduce a person: say 从朋友那儿 or 向朋友).
✗ 自去年，我一直住在杭州 → ✓ 自去年以来，我一直住在杭州 (with 一直 you need 以来 or 起).
✗ 妈妈，我自学校回来了 → ✓ 妈妈，我从学校回来了 (in speech, 自 sounds like a public notice: say 从).