In English you should capitalize:
the first word of a sentence or sentence fragment
a proper name (e.g. the Golden Gate Bridge, the House of Commons)
the name of a holiday (e.g.,Christmas, Easter)
the first word of a direct quotation which is a sentence
a brand name (e.g. Ford Escort)
the pronoun I
These words should also be capitalized in English. Please note that many of the rules that apply to these examples differ from those in Polish.
the name of a day or a month (e.g. Monday, September)
the name of a language (e.g. He speaks French.)
a word expressing a connection with a place (e.g. the American government)
the name of a nationality or an ethnic group (e.g. The Basques are an indigenous ethnic group.)
the name of a historical period (e.g. the Middle Ages, the Industrial Revolution)
the first word, and each significant word, of a title (e.g. The Silence of the Lambs); note that some styles of writing in English prefer not to capitalize all the words in titles, but only the first word of a title and any words which intrinsically require capitals for independent reasons (e.g. The silence of the lambs). It is important to be consistent in the use of the chosen policy within one document.
Rules for capitalizing titles: Common Title Capitalization Rules
The University of Sussex Guide to Punctuation
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