For questions about set of tools that facilitate the delivery, development, and management of applications.

From Wikipedia:

A DevOps toolchain is a set or combination of tools that aid in the delivery, development, and management of applications throughout the software development lifecycle, as coordinated by an organisation that uses DevOps practices.

Generally, DevOps tools fit into one or more activities, which supports specific DevOps initiatives: Plan, Create, Verify, Preprod, Release, Configure, and Monitor.

Another proposed toolchain model was referenced in 2014 as coming from "an unknown source" as Plan, Code, Build, Test, Release, Deploy, Operate and Monitor.

That same Wikipedia page also contains an image showing stages in a DevOps toolchain, which looks like so:

Devops Toolchain stages on Wikipedia