Neither!
Do not italicize:
Scientific names for phylum, class, order, and family, but use initial caps.
No, they do not need to be italicised but they need to be capitalised e.g. Arthropoda, arthropods
Scientific names are composed of the GENUS name, which is capitalized, and the species name, which is always lower case. The entire scientific name is ALWAYS underlined or italicized.
No it should not be italicized. If you are referring to a specific train then it should be capitalized. If the name of the train appears in a title of an article, book etc then it should be italicized in that case.
Not usually, but their initial letters are capitalized as for any title, such as American Centennial World Exposition.
It is not recommend that the title of a PowerPoint be italicized. It is recommended that the author or originator of the presentation be italicized.
No, it is not necessary to italicize airplane names. Proper names for specific models of planes such a the Boeing 787 and the Airbus A380, or an airline name such a Southwest Airlines and Jet Blue Airways are proper nouns and should be capitalized.
By convention the binomial Latin names are always italicized.
No, McDonald's does not need to be italicized.
Yes, orders do not need to be italicized. Orders can be written in regular font.
Names of airplanes, ships, all vessels are underlined or italicized.
Generally, company names are not italicized or enclosed in quotation marks. Product names are often capitalized but can be italicized or enclosed in quotation marks when emphasizing them in a sentence.
Scientific names are composed of the GENUS name, which is capitalized, and the species name, which is always lower case. The entire scientific name is ALWAYS underlined or italicized.
Names of a painting should be italicized.
No. Though individual names of them should be capitalised.
A TV series should be punctuated with italics. For instance, "Friends" or "Game of Thrones".
It depends on the style guide you are following. In general, it is common to italicize the names of churches in written text.
The name of a newspaper is italicized. Underlining is a hold-over from the days of the typewriter, when there was no way to change the actual letters.
Book titles and journal names are typically italicized in a reference list.