A wildcard is a symbol that truncates a word and expands the terms that a database will search on. The symbol varies from database to database but is often *. This can be very useful!
translation: search for puppet, puppets, puppetry
translation: search for theatre, theater, theatrical
example: theater AND theatre
translation: show me only results that contain both theater and theatre [in whatever field you searched in]
example: theater OR theatre
translation: show me results that contain either theater and theatre [in whatever field you searched in]
example: theatre NOT theater
translation: show me only results that contain theatre, and specifically exclude results that include theater [in whatever field you searched in]
Varies by database as to whether it is possible and how it can be performed, but conceptually is a more powerful version of an AND statement or a less restrictive phrase statement.
In JSTOR this can be accomplished using NEAR and paired with either the number 5, 10 or 25
example: theatre NEAR 5 theater
translation: show me results where theater occurs within 5 words of theatre
(this is an absurd example, but will yield results like a chapter Kate wrote which includes the sentence: "The occupation of the Odéon Théâtre de France on May 15, 1968, illustrates how artists and activists can repurpose theater buildings as strategic locations for protest and reenvisioning the world.")
Subject searching means searching using the terms that were applied by an authority to capture the 'aboutness' or category of a publication. Each database will have its own unique subject terms. Some databases have subject terms available to search in a Thesaurus. These often allow you to go directly from the terms to a search. Other databases are more opaque and you'll discover subject terms while browsing a keyword search. Once you know what they are, you can limit your search with them or build them into a search.
Try placing a limit on your search in advance, from the Advanced Search area. Limits to try include: