Microsoft Word allows you to embed fonts in your document, however, the fonts must be TrueType fonts and available for embedding.
The worst thing that could happen is that your text may be unreadable with symbols and boxes substituting characters. This affects the layout and formatting of the document, so the number of pages might not be the same as the original and line and page breaks will not be where you intended them to be. If you share your documents with others and they don't have the same fonts on their system, Microsoft Word will substitute your font with another. The fonts you use in a document determine how that document appears when viewed or printed.
