Quality can be said to be the standard of something as measured against other things of a similar kind; the degree of excellence of something. Also, quality is a distinctive attribute or characteristic possessed by someone or something.

Without much ado, Quality in terms of Steemit Community regarding a post is when a post by a user has justified the following conditions

Images

All images used in the post must be properly reference which means crediting the rightful owner and conforming to the rules of copyright. Also, the recommended aspect ratio for thumbnail images is 16x9. The first image in the post is regarded as thumbnail image and it is automatically switched to be the thumbnail image

Words quantification

Except for certain conditions pertaining to poetry like limericks, the minimum amount of words in a quality post is to be 500words and the maximum is 64,000words.

Plagiarism, Spam, and Abuse

A quality post should avoid plagiarism, spam and abuse. Plagiarism is the practice of taking someone else's work or ideas and passing them off as one's own. Steemit promotes Originality , so therefore content from other source should not be fully adopted and where partially or phrasally adopted, it must be properly referenced. Spam and abuse in the community.

Tags

Tags are a way to categorize your content, and they serve as a template for easy access to post or articles. It is therefore mandated that tags used in post must be closely related to the content of the article. For example, when talking or discussing a person's life, related tags include autobiography, non-fiction, story, blog and so on.
When using this tags, they must all be in small letter casing and tags used are usually not more than five(5).