Trello is a work-management tool built around boards. Teams create cards for tasks, move them across lists and see progress at a glance.

Boards - visual columns for tracking work from start to done.
Cards - tasks with checklists, dates, attachments and comments.
Views - timeline, calendar and dashboard views of the same work.
Templates - ready-made boards for common team workflows.
Mobile apps - boards stay in sync on phones and desktops.

It suits small teams and individuals keeping projects, content plans and to-dos organized. A free plan covers individuals and small teams getting started.