Full-text fields (or just fields for brevity) are the textual document contents that get indexed by Manticore, and can be (quickly) searched for keywords.
Fields are named, and you can limit your searches to a single field (eg. search through “title” only) or a subset of fields (eg. to “title” and “abstract” only). Manticore index format generally supports up to 256 fields.
The text that you send to Manticore gets processed, and a full-text index (a special data structure that enables quick searches for a keyword) gets built from that text. Prior Manticore Search 3.2 the original content of fields is discarded and it’s not possible to fully reconstruct it. In newer versions, original content can be optionally stored in index.