Terraria separates identity from environment: player characters live in .plr files and worlds live in .wld files. That makes a complete backup a two-part job. Copy both directories, including .bak companions, before editing or moving systems. Steam can independently move individual characters and worlds to cloud storage, so an apparently missing local file may have a counterpart under Steam userdata. SaveEditor.com keeps those locations distinct instead of presenting one universal Terraria save path.
Which storefront context matters
Documented Terraria PC launchers/storefronts: Steam, GOG Galaxy. Steam can keep cloud-designated player/world files under its userdata remote tree. The normal local Terraria directory still separates Players and Worlds. The active storefront/account should be identified before any restore because cloud and local storage may not use the same path or container across editions.
Documented cloud behavior
Steam Cloud and GOG Galaxy are documented. On Steam, cloud movement is enabled per character/world rather than being assumed for every local file. Cloud synchronization is useful for continuity, but it can also turn a restore into a conflict-resolution event. Let synchronization settle before making a manual backup, and keep an offline copy outside any folder monitored by the launcher or operating-system sync service.
Local save roots still matter
The researched local save boundary is Windows: %USERPROFILE%DocumentsMy GamesTerraria
Steam cloud copies may appear under <Steam-folder>userdata<user-id>105600remoteplayers and worlds | macOS: $HOME/Library/Application Support/Terraria/ | Linux / Steam Play: $XDG_DATA_HOME/Terraria/ (normally ~/.local/share/Terraria/); the known file or folder pattern is Players*.plr
Worlds*.wld
*.bak. A cloud-enabled game still has concrete local data involved in ordinary play, and that local context is what you need when identifying which copy was modified most recently.
Avoid accidental overwrite loops
Back up both Players and Worlds plus their .bak files. If a character and world belong together, keep them in the same dated archive even though they are separate files. When restoring, close the game and launcher, preserve both the current local copy and the backup you want to test, then place the intended data in the matching profile/storefront location. Do not repeatedly open the game between different copies without noting which side the cloud client selected.
Compatibility and conflict checks
A world file and a player file have different structures and cannot replace one another. Cloud status can also differ per file. If progress disappears or rolls back, If a character or world is missing, check both the local directory and Steam remote location. Before using a .bak copy, preserve the current .plr/.wld and the backup so the recovery remains reversible. Resolve identity/path/cloud questions first. A cloud conflict is not proof that the save itself is corrupt, and a successful upload is not proof that files from another storefront are compatible.
Verification context: Windows/macOS/Linux locations, .plr/.wld patterns, Steam remote paths, and per-item Steam cloud behavior were reviewed against current PCGamingWiki coverage.