Most websites contain content that doesn't come from the website's source itself but from other sources, f.e. advertisements or applications that enrich the functionality like Geo-location information.
This 3rd. party-content isn't always harmful (mostly not), but sometimes it can be, with or without knowledge of the website-developer. Advertisements, links and downloads can point to something else than they say they do and sometimes even the malicious content isn't visible and installs itself automatically on the visitors' computer or does other harmful things like taking over user-sessions, stealing cookies, spying on user-input and much more.
Luckily most webbrowsers show warnings when a person wants to visit a website that contains deceptive or harmful content, but that might not be always the case.
Best is to stay away from this kind of websites in the first place and especially not clicking on any link, advertisement or pop-up screen if you are not 100% sure that it comes from and/or points to a safe location. When you want to be sure that you have all the latest updates, always go to the software-manufacturers' website itself and retrieve them from there if necessary.
Another good tip is doing a websearch for reviews on the specific item, if there's something wrong with it you mostly will see that in the reviews. Just stay away from non-reviewed sources and applications.
Deceptive/dangerous website/pages
A deceptive website is a website that contains social engineering or phising techniques, these usually fake sites try to trick you into revealing personal information, passwords, downloading unknown applications like (fake) virusscanners, installing a (fake) update etc. A dangerous website contains malware that can harm your device, often this happens just by visiting such a website or clicking on a link which contains malware that automatically installs itself on your computer or mobile device.
Not all website-developers put deceptive- or malicious content on their websites on purpose: a lot of sites are being hacked, while the owner of the website doesn't know about it. Browsers mostly give a warning that such a site is ahead when you are browsing the web, this helps a website-developer ánd his visitors to be noticed that something is wrong. For webdevelopers there are many tools and scanners that they can use like Google Search Console and Bing Webmastertools. Online scanners scan a website for vulnerabilities and harmful content.
A lot is being done against these kinds of websites, where Google is the forerunner: they have a list of dangerous or deceptive websites and show a warning in the Chrome-browser when you try to visit such a page. Google also maintains a list of trusted sites. This list is being used by other browsers too, like Edge, Firefox and Opera. Next to that, the Google Chrome-browser has a safe-Browsing functionality which warns you when you are going to visit a deceptive or unsafe website. Lots of other browsers have such an option too, enter the settings-page of your browser to see what options there are. To protect yourself against online malicious activities it is best to stay away from these websites and never to download anything "just because" a pop-up screen on a website tells you that there's something wrong. Whenever you are worried about your safety, visit a legitimate website for malware- and virusscans and always use the update-functions that are being provided by the software-companies from whom you have your webbrowser, operating system etc.
