Sentence case is a capitalisation style that treats a heading like an ordinary sentence: only the first word and any proper nouns are capitalised, and everything else is lowercase. For example, the title "how to install python on a mac" in sentence case is "How to install Python on a Mac" — "Python" and "Mac" stay capitalised because they are proper nouns, but "install" and "on" do not, even though title case would capitalise them.
Modern editorial and design practice increasingly favours sentence case for headlines, subheadings, buttons, and UI labels. Major design systems (including those from Google, Apple, and many product teams) default to it. The reasons are practical: sentence case reads as more conversational and less shouty than title case, it is easier to apply consistently because there is no per-word judgement about which minor words to lowercase, and it handles proper nouns and edge cases the same way normal writing does. It also tends to be faster to read at a glance.
The main decision point is proper nouns — names of people, places, brands, products, days, and months stay capitalised, while common nouns do not. This is exactly where automated conversion can slip, since a tool cannot always tell that "apple" the fruit differs from "Apple" the company, so a quick human check is worth doing after any bulk conversion. Sentence case sits opposite title case on the formality spectrum: title case for traditional book and article titles, sentence case for a cleaner, contemporary voice. Switch any text between the two styles instantly with our letter case converter.