Search engines and social platforms read a page differently from a person. They look at the title tag, the meta description, the heading structure and the Open Graph tags, and they apply their own truncation rules. The tools here let you see that version of your page before you publish it, which is when mistakes are still cheap to fix.

The most common problems are boring and easy to avoid: a title that gets cut off in results because it runs past roughly sixty characters, a missing description that leaves Google to invent one from your body text, multiple H1 tags confusing the page hierarchy, and no Open Graph image so shared links appear as a bare grey box. Check those four before worrying about anything more advanced, because they affect whether people click at all.