Beyond the default black dot
Word's default bullet character is a plain, functional dot, chosen for being unobtrusive rather than distinctive. For a document where visual identity matters -- a branded proposal, a styled newsletter, a portfolio -- a custom bullet can reinforce that identity in a small but consistent way every time a list appears, without needing any design software beyond Word itself.
Symbol vs. picture bullets
The Symbol option pulls from any installed font's character set, which includes arrows, checkmarks, geometric shapes, and other characters well beyond the handful shown by default -- useful for a quick style change with no extra files needed. The Picture option goes further, letting you use any saved image file as the bullet itself, which is how a small company logo or custom icon ends up as a list marker, though it's worth keeping the image simple and small so it reads clearly at bullet size.
Frequently Asked Questions
Will a custom bullet look the same if I share the document with someone else?
A picture bullet is embedded in the document and will display consistently for anyone who opens it. A symbol bullet from an uncommon font may not display identically if the recipient doesn't have that font installed.
Can I go back to the default bullet style later?
Yes -- selecting the list again and choosing one of the standard bullet options from the same dropdown menu replaces the custom bullet without affecting the text itself.