mimi

In Swahili, you generally don't need a separate word for "I" to make a complete sentence. The verb already has the first-person singular subject ni- built into it (for example, ninasoma means "I am reading"). However, with the present copula words ni (am/is/are) and si (am not/is not/are not), there are no subject prefixes. You usually need to use mimi to establish who you are talking about out of the blue (e.g., Mimi ni mwanafunzi - I am a student), though it can be dropped if the context is already clear.

So, when do you actually use mimi?

• For Emphasis: To say "As for me..." or "I myself..."
• For Contrast: To compare yourself to someone else (e.g., "You are a student, but I am a teacher").
• Standing Alone: To answer a question like "Who is it?" with "Me!"
• With the Habitual Tense: The habitual hu- tense lacks subject prefixes, so you need mimi to specify the first person singular (e.g., Mimi husoma - I usually read).
• After Certain Prepositions: To mean "me" after words like kama (like), na (with), or bila (without). Warning: Associative prepositions like kwa (to/for) or badala ya (instead of) require the possessive stem -angu instead (e.g., kwangu, not kwa mimi, though you might hear kwa mimi in Kenyan colloquial speech).
• As a Direct Object (Emphasis Only): Normally, "me" as an object is expressed by the object marker -ni- inside the verb (e.g., ananiona - he sees me). You only add mimi after the verb for heavy emphasis (e.g., ananiona mimi - he sees me).

Special Forms & Shortenings: In everyday spoken Swahili, mimi is frequently shortened to mi (e.g., Mi naenda - I am going). Furthermore, mimi can fuse with certain small words. For example, na (and/with) + mimi often becomes nami (and me / with me). It also fuses with the emphatic copula ndi- to form ndimi (It is I / I am indeed), and with the negative copula si- to form simi (It is not I). Note that simi is mostly literary or archaic; everyday modern Swahili prefers si mimi or siyo mimi.