Information available on the internet can be very valuable, completely useless or anywhere in between. It is sometimes very difficult to tell if information you find can be trusted. There are many time I have had to simply disregard information I found because I could not verify how true it was. Below are some criteria I use when doing research on the internet:
Website Domain - .edu, .org, .com; Pretty much in that order of preference. A ".edu" is a site associated with an educational institution. I tend to trust the information found on these sites the most. A ".org" is a site from a non-profit organization. Not that you can automatically trust these sites, but I have found them to be a bit more reliable as long as you realize that their organization may make them a bit biased in some respects. A site with a ".com" extension is a standard commercial site. I tend to look for these last. Again, not that the information cannot ever be trusted.
Dates - If you are looking for current information on a recent topic and the page you find has no indication of when the information was published (or the information is obviously outdated) you can't really trust it to be up to date and accurate. Look for dates at the top of the page; look for revision dates in the footer; scan the information for dates mentioned. You need to know something about what you are looking for, before beginning your research. Information on the Civil War that was published in 2002 may be accurate and current where information on the planet Mars may not be.
Footnotes, Citations, References, Quotes, Etc. - All of these things indicate that what you are reading isn't just the opinion of the person who created the webpage.
Abstract or Summary - Most "official" reports will contain an abstract.
Data and Analysis of Results - This would indicate that real work was actually done before the information was written.
It's important to remember that none of the above can be considered definite proof that what you are reading is authoritative, objective, reliable and current information. Also, there are many internet sites that have authoritative, objective, reliable and current information but do not agree with what's above. The best approach is to use multiple sites from a variety of resources that agree on the information you are researching.
I hope this helps.