Master Slides, Themes, and Templates
Domain focus: the inheritance chain that makes a deck editable and consistent - theme, slide master, layouts, then individual slides.
The hierarchy
A theme supplies theme colours (four text/background plus six accents), theme fonts (Heading and Body), theme effects and background styles. A slide master holds the layouts. Layouts hold placeholders. Slides inherit from their layout unless someone applies direct formatting or deletes a placeholder. Handout and Notes masters are separate and do not affect slides.
Working in Slide Master view
Insert Layout creates a new layout; Rename keeps it findable; Preserve stops an unused master being dropped on save. Placeholders added on a layout appear on slides using that layout, so put logos, title bands and footer elements on the master or layout - never on individual slides. Insert > Themes > Save Current Theme writes a .thmx; saving the file as .potx makes it a reusable template. Slide Size changes the aspect ratio, which scales content and repositions placeholders, so set it before designing.
Worked example
A brand requires light content slides and dark section dividers. Solution: one master with two layout families, not two masters, so theme colour edits propagate in one place; the divider layouts simply use a different background fill. Reasoning: multiple masters multiply maintenance and break "Reset to Theme" expectations, while multiple layouts on one master stay consistent.
Traps that cost marks
Direct formatting that survives theme changes and breaks consistency; deleting a placeholder on a slide instead of on the layout; a different master per section by accident; assuming theme colours equal standard colours; forgetting that footers and slide numbers are placeholder-driven.