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Which atomic numbers belong to the actinoid series?

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A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — actinoid element Modern version of the periodic table of the elements (printable).

The actinoid series consists of 15 consecutive chemical elements in the periodic table, spanning atomic numbers 89 through 103.1

While some sources define the series as beginning after actinium (atomic numbers 90–103), the International Union of Pure and Applied Chemistry recognizes the group as including elements 89 through 103. These elements, also known as actinides, are characterized by their radioactivity and include both naturally occurring elements like uranium and various man-made elements.12