FAQ: CSS Setup and Selectors - Review CSS Selectors


This community-built FAQ covers the “Review CSS Selectors” exercise from the lesson “CSS Setup and Selectors”.

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This exercise can be found in the following Codecademy content:

Web Development

Learn CSS

FAQs on the exercise Review CSS Selectors

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Can we use publish_time instead of publish-time for a selector in CSS? Is it Mandatory to use publish-time


‘‘Classes can be reusable, while IDs can only be used once.’’
i dont understand this


There may be 30 students in a classroom, but each have a unique id, else how would we know who’s grade it is posted on the exam board. There are no names on the list, only numbers, and only the student knows their own number (besides the examiner).

An ID is very specific, and pertains to just one thing. It can be small or it can be large, but it is most definitely singular. There can be only one.

Classes on the other hand are nebulous and ubiquitous. They are everywhere and can pertain to all manner of objects. That’s why they are re-usable.