Dehydrohalogenation is a $\beta$-elimination reaction where a hydrogen halide ($HX$) is removed from an alkyl halide in the presence of a strong base (like alcoholic $KOH$).

• Saytzeff's Rule (Zaitsev's Rule) states that in an elimination reaction, the most substituted alkene (the one with the most alkyl groups attached to the double bond) is the preferred or major product.
• Stability: Highly substituted alkenes are more stable due to hyperconjugation.
• Example: 2-Bromobutane gives 2-Butene (major) rather than 1-Butene.