Why do authors make certain words bold, italicized, or underlined?

Answer above be like:

women should get jobs in the war industries

explanation:

during the time of the war women usually stayed back and got jobs to support the war by making bullets and machinery used in the war.

hope this

- three-quarters or two-thirds..

- "the constitution provides that an amendment may be proposed either by the congress with a two-thirds majority vote in both the house of representatives and the senate or by a constitutional convention called for by two-thirds of the state legislatures."

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