WikiMatrix lists a plethora of features for each wiki engine. Select a feature from the list below to get some in-depth description and feel free to improve the documentation
Does the wiki engine store your contents in plain text files?
This may be an optional feature (allows choosing between this or other data storage mechanisms). The mechanism may involve using just one big file, but more typically they will create one file per wiki page. Files may be kept in a directory structure matching your use of Namespaces, files may contain only the wiki text, or may be wrapped in XML markup tags and/or include escape character encodings.
Some web hosts do not allow file writing operations from scripts. Check this before attempting to install such a wiki. You may need to go for a wiki that writes its data to database tables instead (e.g. if you web host provides MySQL).
Note that we are talking about the storage mechanism of the wiki. Some wikis do not store data in flat files, but have an *export features* e.g. Raw Export, HTML Export, XML export, or PDF Export. Using flat text files is a popular alternative with some advantages and disadvantages over storage in database tables.
Flat file storage may seem a lot more natural for you as a wiki administrator, since each page is a document on your filesystem, which you can browse/edit/manipulate using whatever command-line or operating system file handling utilities you like. However with many complex wiki engines it is not advisable to carry out such manipulations directly on files anyway.
Flat files can be zipped up and kept as a backup (and restored) quite easily. Databases should be easy to backup too, but you will need to learn how.
In general databases are easier/faster to search
In general databases can be expected to scale better.
This is why wikis using flat file storage will usually have to fall back on some sort of database for full text searches. This does not necessarily mean a relational database; it could just as well be a system built upon gdbm or similar libraries.