An appositive or apposite is a word or group of words juxtaposed besides a noun or pronoun to provide further information about them. They could come before or after the noun or pronoun that they modify. In the first sentence, Ottawa is the noun that was further described as the capital of Canada. The sentence would still be complete without the addition of the appositive phrase.
In the second sentence, the appositive, older provides further description about the noun, sister. In the third sentence, the appositive phrase identifies the breakfast. Appositives are additional information without which, the sentence will still stand.
