I might use it as a starting point, or to jog my memory for something I already know (date or other factoid). But while studies show that Wikipedia is about as accurate overall as Encyclopedia Britannica, there's always the chance that an uncorrected error has been posted. So I wouldn't use it as my only, or even my primary source.
I'm about the same. Generally, I don't find encyclopedia-style secondary sources that useful, except for double-checking, or making sure I haven't missed something obvious. For my period (19th century), Google Books restricted by date is much more useful, as well as similar collections of primary source material online like Making of America, Documenting the American South, etc.
Good example just this morning. The topic of food adulterations came up. I remembered there was an English doctor who brought the topic to notice in the 1850s, and interest expanded and spread through the 1860s. Originally, I'd found that out because I noticed articles on food adulteration when reading period magazines and newspapers, and noticed that most traced back to the same doctor as their inspiration.
But I couldn't remember his name. So I searched on Google Books for "food adulerations" restricted to pre-1870, and recognized the name of Arthur Hill Hassall, who was listed as an author of an 1855 book that was online. His book itself would have been the first stop for specific information on poisonous substances found in a particular food. However, in this case, I was more interested in the trend itself, and though there were a few earlier books on the topic, I wanted to make sure that Hassall was indeed a major figure in this field.
So I put his name in a regular Google search, saw a Wikipedia entry, clicked on that, and confirmed, "
In the early 1850s he also studied food adulteration; his reports were published in The Lancet by reformer Thomas Wakley and led directly to the 1860 Food Adulteration Act and subsequent further legislation against the practice."
The Wikipedia entry was useful to indicate that I had the right fellow and that I hadn't missed anything obvious, but to find out that food adulteration was a topic of interest in the 1860s in the U.S. in the first place, despite no significant legislation occurring here until later, isn't something that one could easily come across in Wikipedia, compared to primary sources.
). I'd agree with Marlys - when I'm researching a topic, it's a good place to start to get an idea of what to research in depth. It's also quite good for its 'external links' sections a lot of the time. I did a lot of work once on extinct European languages and found a lot of dictionary sites, that sort of thing from those links.
