1. **State the problem:** Simplify the expression $\frac{100-100}{10-10}$.\n\n2. **Apply the formula:** The expression is a fraction where the numerator is $100-100$ and the denominator is $10-10$.\n\n3. **Calculate numerator:** $100-100=0$.\n\n4. **Calculate denominator:** $10-10=0$.\n\n5. **Evaluate the fraction:** $\frac{0}{0}$ is an indeterminate form, which means it is undefined in standard arithmetic because division by zero is not allowed.\n\n6. **Conclusion:** The expression $\frac{100-100}{10-10}$ is undefined because the denominator is zero.