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Measurement
TMS
Tag management system
A TMS is the layer that decides what loads on the page, when, and with which data. It centralizes tags, trigger rules, and extensions so the site code does not change for every update.
- When it applies
- It fits when several teams and vendors measure the same site without colliding, and when the pace of measurement change cannot depend on the release calendar.
- What it is confused with
- It is not a box where scripts get pasted. Every tag added inherits access to the data layer and to the user browser, so an ungoverned TMS is an open permission handed out to vendors.
- Architecture consequence
- What you inherit constrains years of work. A profile with hundreds of unused keys, duplicated rules, and vendors long gone forces a risk-first audit before touching anything, and that audit is the work, not the preamble.