Margaret comes from the Greek margaron, meaning "pearl." The same root gives Greta, Marguerite, Maggie, Margot, and Daisy (which is named for the marguerite flower — the daisy in French is la marguerite).
Margaret has been borne by queens, saints, and Pulitzer Prize winners. Today the formal name is returning quietly — currently in the U.S.
Margaret does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Margaret reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.