A grain bill is really two separate decisions layered on top of each other: which malts will actually convert their own starch into fermentable sugar (the base malts, chosen mostly for their enzyme content and clean flavour), and which malts are there purely to season the result (crystal, roasted and specialty malts, added in small percentages for colour and flavour rather than fermentable extract).
Every entry here gives the malt's typical colour in degrees Lovibond — the scale that also feeds directly into the SRM colour calculator — along with a conventional maximum share of the grain bill where one exists, its flavour character, and its diastatic power in degrees Lintner where the malt type has meaningful enzyme content. Diastatic power matters more than most homebrewers think about day to day: a malt with real diastatic power can convert not just its own starch but some of an adjunct's, which is exactly why a mash heavy on flaked oats or corn still converts cleanly when it's built on a base of well-modified two-row or Pilsner malt.
The categories break down the same way most maltsters organise their own catalogues: base malts (the bulk of nearly every grain bill, chosen for enzyme content and a clean flavour base), crystal or caramel malts (kilned while still wet, producing unfermentable sugars that add sweetness, body and a caramel-to-dried-fruit flavour range depending on how dark they're roasted), roasted malts (kilned dry at high temperature for coffee-to-burnt character with essentially no diastatic power), adjuncts (unmalted or lightly processed grains added for body, head retention or cost, contributing little to no flavour of their own), and specialty malts (a catch-all for everything that doesn't fit neatly elsewhere — smoked malts, acidulated malt, honey malt, and similar).
A specific bag's colour will vary by maltster and by production lot even for malts with the same name — Weyermann's Munich and Briess's Munich are not identical products — so treat every figure here as the commonly-cited typical range for the malt type, and check the maltster's own current spec sheet before finalising a recipe you care about precisely.
Once you've settled on a grain bill, run it through the SRM colour calculator to see the actual colour it's likely to produce, and cross-check the total against the style guideline page for whatever you're brewing.