I am trying to get data from the web using Python. I imported urllib.request but while executing I got: certificate verify failed: unable to get local issuer certificate (_ssl.c:1045) I am using Python 3.7 on Mac OS High Sierra and am trying to get this CSV file. When I changed the URL to http I was able to get the data, but this avoids checking the SSL certificate. Run /Applications/Python\ 3.7/Install\ Certificates.command solved my problem. But how exactly did this solve my issue? My question differs from openssl, python requests error: "certificate verify failed" because I want to know what actually happens when I install certifi package or run Install\ Certificates.command to fix the error. Continue reading...