The samples that follow all quote, appropriately or inappropriately, from page 89 of Politics and the Media in Canada (2nd edition) by Arthur Siegel:

The social and economic changes brought about a stable environment favourable to the development of newspapers, which began to spread rapidly. There were 20 papers in the four eastern provinces of Upper and Lower Canada, New Brunswick, Nova Scotia, and Prince Edward Island in 1813; by mid-century, there were nearly 300. Each developed a local personality related to the community of publication, and the newspaper became the disseminator of local news when gossip could no longer do the job efficiently.

Plagiarism:

In the early 1800s there were 20 papers in the four eastern provinces of Upper and Lower Canada, New Brunswick, Nova Scotia, and Prince Edward Island.

(This quotation, which uses most of the source's sentence without even acknowledging that the information comes from a source, is plagiarized. Ideas and words from a source cannot be included as if they were your own – you must give credit to the original writer.)

Correct quotation:

According to Arthur Siegel, "there were 20 papers in the four eastern provinces of Upper and Lower Canada, New Brunswick, Nova Scotia, and Prince Edward Island in 1813" (89).

Plagiarism:

Siegel observes that social and economic changes brought about a stable environment favourable to the development of newspapers (89).

(This quotation is plagiarized because it uses the exact words of the source – most of a sentence – without quotation marks.)

Correct quotation:

Siegel observes that "social and economic changes brought about a stable environment favourable to the development of newspapers" (89).

Plagiarism:

According to Siegel, a Canadian newspaper in the 1800s was characterized by a local personality related to the community of publication (89).

(This is plagiarism because exact words – "a local personality related to the community of publication" – from the original source are not acknowledged as borrowed.

Correct quotation:

According to Siegel, a Canadian newspaper in the 1800s was characterized by "a local personality related to the community of publication" (89).

Misleading quotation:

Siegel writes that "the local newspaper developed a local personality related to the community of publication" (89).

(This sentence is unacceptable because it claims to be a direct quotation, but the words have been changed.)

Correct quotation:

Siegel writes that "each [local newspaper] developed a local personality related to the community of publication" (89).

Misleading quotation:

In his historical discussion of of newspapers, Siegel points out that "social and economic changes brought about the development of newspapers, which began to spread rapidly" (89).

(This sentence is unacceptable because the writer has not used ellipsis marks to indicate where words have been omitted from the quotation.)

Correct quotation:

In his historical discussion of of newspapers, Siegel points out that "social and economic changes brought about [...] the development of newspapers, which began to spread rapidly" (89).