Cutting down on unnecessary words minimizes extraneous cognitive load, which is a barrier to learning. Germane cognitive load, which promotes learning, can be assisted by using conversational language (e.g., speaking to the user in the second person). (pp. 6-7)
Average users of a website only read 20-28% of the words on a page. You should "cut writing in half, and then cut it in half again." Avoid unnecessary words, use plain language, and speak to the user as "you." (Tip #5)