Hello, I'll build a website and share resources there. I want to put a text (approximetely 100 words) on every article that users can learn how to install that resource in the same page. Would this effect SEO? Is using same text in every article a problem?
Yes pages with content exactly the same is duplicate content and most likely will not be indexed due to duplicate content. Ensure the content in page specific if there is a small part duplicated not an issue just if most of the content is duplicate it's an issue. Another way around it is if you have a large chunk that will be duplicate consider serving that information on a separate page like a how to install page, then the information won't be duplicated on multiple pages.
Thank you for answer. I want to tell more about my question. The text that I can write is up to 300 words because the content is limited. The reason I want to duplicate content is to have more words in article. But as I understand, duplicating content is worse than articles with less words, right?
I think you can do this, but keep this copy pasted text somewhere at the bottom of the rest of the content. If you can change it little bit, some words here and there, even better.
It is not true that the duplicated content will not index by Google most of the time it will be indexed but will not recommend in the searches.
At the close of every one of my website's ~460 articles, below a visible dividing line, I have some identical text repeated on each page, along with the brief copyright information. • One sentence invites them to use the adjacent Custom Search box to find more topics of interest. • The other text is a short invitation to share the page if they have enjoyed it. If you wish to see a sample page with the repeatable text I put at the close of every page, scroll to the bottom of https://www.jimfeeney.org/virtuous-woman-eyes-God.html I'm confident that the search engines completely understand the purpose of this always-repeated closing text. I've never seen any penalization of this usage on my website. However, do not use the bottom of each page for "footer spam" — that is, a bunch of links-with-keywords that do not relate to your page's topic. You will be penalized for that.
Duplicate content is one of the major issues in SEO. It's something basic that Google wants original content, so I would not advise having the same article/text pasted in multiple places.