We has been part of English since Old English, having come from Proto-Germanic *wejes, from PIE *we-. Similarly, us was used in Old English as the accusative and dative plural of we, from PIE *nes-. The following table shows the old English first-person plural and dual pronouns:
By late Middle English the dual form was lost and the dative and accusative had merged.:117 The ours genitive can be seen as early as the 12th century. Ourselves replaced original construction we selfe, us selfum in the 15th century, so that, by century's end, the Middle English forms of we had solidified into those we use today.:120
We is not generally seen as participating in the system of gender. In Old English, it certainly didn't. Only third-person pronouns had distinct masculine, feminine, and neutre gender forms.:117 But by the 17th century, that old gender system, which also marked gender on common nouns and adjectives, had disappeared, leaving only pronoun marking. At the same time, a new relative pronoun system was developing that eventually split between personal relative who and impersonal relative which. This is seen as a new personal / non-personal (or impersonal) gender system.:1048 As a result, some scholars consider we to belong to the personal gender, along with who.
The contracted object form 's is only possible after the special let of let's do that.
The editorial we is a similar phenomenon, in which an editorial columnist in a newspaper or a similar commentator in another medium refers to themselves as we when giving their opinion. Here, the writer casts themselves in the role of spokesperson: either for the media institution who employs them, or on behalf of the party or body of citizens who agree with the commentary. The reference is not explicit, but is generally consistent with first-person plural.
The author's we, or pluralis modestiae, is a practice referring to a generic third person as we (instead of one or the informal you):
We in this sense often refers to "the reader and the author" because the author often assumes that the reader knows and agrees with certain principles or previous theorems for the sake of brevity (or, if not, the reader is prompted to look them up). This practice is discouraged by some academic style guides because it fails to distinguish between sole authorship and co-authorship. Again, the reference is not explicit, but is generally consistent with first-person plural.
Some languages distinguish between inclusive we, which includes both the speaker and the addressee(s), and exclusive we, which excludes the addressee(s). English does not make this distinction grammatically, though we can have both inclusive and exclusive semantics.
We is used sometimes in place of you to address a second party: A doctor may ask a patient: "And how are we feeling today?". A waiter may ask a client: "What are we in the mood for?"
According to the OED, the following pronunciations are used: