Simply put, PERSI is short for PERiodical Source Index, a name, place, and subject index to periodicals (magazines, newsletters, journals) in the areas of genealogy and local history, published in the last 200 years, in English, and in French Canada. Librarians sometimes refer to such periodicals as serials.
Why is this important to your genealogical and local history research? Here's a clue. You live in northern California; your family is originally from southern California. Well, not really. They came from New York State in the late 1800s. They had worked their way across New York since arriving from Europe in the middle of the 19th century.
So if a New York area genealogy or history group (the most likely) publishes an article on names or places that are of interest to you, how will you find it being 3000 miles away? You can't afford to subscribe to, or have the time to read, every periodical that comes out. Nor can your local library afford to do the same. Think of this. Some periodicals are published monthly; some quarterly; some annually. Each hopefully has an index. So when you look at them you have to examine perhaps a dozen indexes per year (unless you are lucky and they cumulate). And when you find an item, you have to get a copy. But the item is 140 years old and can't be photocopied.
I became familiar with PERSI during the1970s and knew it as a photocopied letter-sized publication. It became available on CD in the 1990s, and now is available online at commercial sites. Who are the brains behind the web pages? You can credit the fine folks at the Allen County (Fort Wayne, Indiana) Public Library for the task of setting up the idea of indexing and creating the original PERSI. I would estimate that there are several thousand periodical titles covered and in excess of a million entries in the collection. He paper version eventually grew to several dozen volumes and cost several thousand dollars, so it's pretty clear why many people did not know about it or own it.
What it is — PERSI is an index to names and places in magazines. It is NOT an index to every name on every page of every magazine. It contains references to cemeteries, church records, places, histories, and land records, as well as to people and their biographies.
I have used the version available through Heritage Quest Online, and note that for my own area, it references the title of a local quarterly—Heritage Quest Online is available at many libraries. Having found a title, I can then click though set up pages to order a copy online for a fee. The difference is -- we have a thorough index to the quarterly at the reference desk at our library and can check out or make copies of the pages from this quarterly for a very modest amount; but if you find a hit that is interesting to you from a far distance away, you can order it for a reasonable sum online from HQ. With gasoline being so expensive, and time for research trips being at a premium for many of us, the trade off of money for access seems reasonable.
How is the index used? I confine myself to the version we have access to at work. You can search people in the Search People section, and you can further limit your search by record type and even add a third keyword in another field to help narrow down. And yes, I have had a question about a Mr. Smith Brown in New York. Thanks goodness for the possibility of limiting the results!
Searching places is also handy. The user can enter a U. S. state, county, a Canadian province, another country, and other keywords or record types. The version on HQ allows the user to browse tables of contents
Think about what this covers and time it saves. If what you are looking for isn't in PERSI, or you have a bit of difficulty finding it, remember that it is saving you the effort of traveling to read these publications and locate them all. It's like complaining that the hippo dances badly. It's a miracle that it dances at all.
Before I run out of column, let's try a practice search. I wanted to know about the Brooker family of New England. I went to the Search People page of the online version, entered the surname, and got 18 hits. While this family may be written about anywhere, the one that grabbed my eye right away was the family of Abraham Brooker of Connecticut. But was the information published there? No, it is in the periodical Your Ancestors, published in Detroit, Michigan, May 1948, Volume3, issue 5. If I want to order it, one click takes me to the Allen County library order page, and I see that the charge is $7.50, pre-paid, plus $0.20 per page copied to be billed. Requests are not acceptable by phone, fax, or e-mail – you must snail mail them. The library also advises you to expect a wait of 6-8 weeks. However, I also saw an entry for Joanna Brooker's will, 1763, MA. That appeared in the New England Historical and Genealogical Register published in Boston, MA: Apr 1908. Vol. 62, Iss. 2. This is in my own library's holdings, so if you know that your local library has a good collection, you can use this search to help you search quickly.
The last test was for church records, and this appears: First Presbyterian records, 1825, Rochester, in the magazine Genealogy, from New York, NY: Sep 1912. Vol. 2, Iss. 10. Interesting, as very few records survive from nearly 200 years ago.
So there's a quick look at a very useful magazine index. It may well be available through you local library's online services, so give it a look.