Do ATS systems automatically reject most resumes?

Not usually on resume quality alone. Knockout questions can screen applications out, and recruiters then search and sort the rest, so clear, relevant wording matters.

Should I send a PDF or a Word document?

Follow the posting. If it does not say, a text-based PDF or a Word document is usually read well by modern systems.

Can an ATS read tables and columns?

Some systems handle them poorly and may mix up the order of your text. A single-column layout is the safest choice.

How ATS resume screening works

What an applicant tracking system (ATS) does with your resume, how keyword and meaning-based matching work, and the format choices that matter.