it's

• i's (eye dialect)
• 't's (eye dialect)
• it'sa (pseudo-Italian)

• IPA^(key): /ɪts/

• Audio (US):

  (file)

• Rhymes: -ɪts
• Homophone: its

Contraction of ‘it is’, ‘it has’ or 'it was'.

it’s

1. Contraction of it is.

   it’s too expensive;  it’s coming right for us!; it's a free country

   • 1743, Martin Marley, The Good Confessor, page 307:

     [...], guided not by his own Will, but by the Medick Science, which dictates, that it's recessary, beneficial, and convenient to alter, mix, and temper this medicine, and fit it to the Disposition, and Constitution of the Patient[.]

   • 2013 June 21, Oliver Burkeman, “The tao of tech”, in The Guardian Weekly, volume 189, number 2, page 48:

     The dirty secret of the internet is that all this distraction and interruption is immensely profitable. Web companies like to boast about […] and so on. But the real way to build a successful online business is to be better than your rivals at undermining people's control of their own attention. Partly, this is a result of how online advertising has traditionally worked: advertisers pay for clicks, and a click is a click, however it's obtained.

2. Contraction of it has.

   It’s been a long time since I’ve had cheesecake.

3. Contraction of it was.

   It’s the same stoneground flour from this week that we used to make last week's strudel.

   • 2016, Dominique Roques, Pico Bogue - Volume 4 - Striking the Balance‎, page 31:

     I guess for you it's the past that had a surprise in store.

4. (dialectal) There's, there is; there're, there are.

   it's a fine line between love and hate; it's a package for you by the door

• See Usage under “its”

• (it is): ’tis
• (it was): ’twas

From it +‎ -’s (possessive marker).

it's

1. Obsolete form of its.
   • 1603, Michel de Montaigne, chapter 43, in John Florio, transl., The Essayes , book I, London: Val Simmes for Edward Blount , →OCLC:

     The manner wherewith our Lawes assay to moderate the foolish and vaine expences of table-cheare and apparell, seemeth contrarie to it’s end.

   • 1767, George Canning, “Anti-Lucretius”, in Poems‎, London: for the author, page 281:

     Behold the balanc’d Scales suspended stand,
     Neither a jot inclin’d to either hand:
     But place the smallest grain of weight in one,
     Straight the fraternal equipoise is gone;
     The loaded scale, preponderant, downward flies,
     Drags down the chain, and makes it’s [sic] partner rise.

   • 1787, “Article I”, in United States Constitution:

     No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing it's inspection Laws[.]

   • 1803, President Thomas Jefferson, Instructions to Captain Meriwether Lewis:

     The object of your mission is to explore the Missouri river, & such principal stream of it, as, by it’s course & communication with the waters of the Pacific Ocean.

   • 1815 December (indicated as 1816), [Jane Austen], chapter IV, in Emma: , volume III, London: for John Murray, →OCLC, page 60:

     It’s tendency would be to raise and refine her mind—and it must be saving her from the danger of degradation.

   • 1848, Treaty of Guadalupe Hidalgo‎:

     Article V.
     The Boundary line between the two Republics shall commence in the Gulf of Mexico, three leagues from land, opposite the mouth of the Rio Grande, otherwise called Rio Bravo del Norte, or opposite the mouth of it’s deepest branch, if it should have more than one branch emptying directly into the sea; from thence up the middle of that river, following the deepest channel, where it has more than one, to the point where it strikes the southern boundary of New Mexico; thence, westwardly, along the whole southern boundary of New Mexico (which runs north of the town called Paso) to it’s western termination; thence, northward, along the western line of New Mexico, until it intersects the first branch of the river Gila; (or if it should not intersect any branch of that river, then, to the point on the said line nearest to such branch, and thence in a direct line to the same;) thence down the middle of the said branch and of the said river, until it empties into the Rio Colorado; thence, across the Rio Colorado, following the division line between Upper and Lower California, to the Pacific Ocean.

   • 1876, Mark Twain [pseudonym; Samuel Langhorne Clemens], chapter XXIX, in The Adventures of Tom Sawyer, Hartford, Conn.: The American Publishing Company, →OCLC, page 219:

     The mouth of the cave was up the hillside—an opening shaped like a letter A. It’s massive oaken door stood unbarred.

2. Misspelling of its.

• SIT, 'tis, Sit, IST, TIs, t'is, tis, STI, TIS, is't, ist, sit, -ist, Ist, TSI, S.T.I.

• IPA^(key): /ɪts/

it's

1. Contraction of it is.

   Synonym: tis

   • 1867, “THE BRIDE'S PORTION”, in SONGS, ETC. IN THE DIALECT OF FORTH AND BARGY, page 102:

     A portion ich gae her, was (it's now ich have ee-tolth)

     The portion I gave her was (it's now I have told)

   • 1867, “ABOUT AN OLD SOW GOING TO BE KILLED”, in SONGS, ETC. IN THE DIALECT OF FORTH AND BARGY, number 2, page 106:

     Ich aam a vat hog it's drue. Aar is ken apan aam.

     I am a fat hog, 'tis true. There is ken upon them.

• Jacob Poole (d. 1827) (before 1828) William Barnes, editor, A Glossary, With some Pieces of Verse, of the old Dialect of the English Colony in the Baronies of Forth and Bargy, County of Wexford, Ireland, London: J. Russell Smith, published 1867, page 102