Abstract Fungicides are indispensable for high‐quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site‐specific fungicides has principally been linked to target and non‐target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti‐resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non‐target sites of quinone outside inhibitor (QoI) fungicides, methyl‐benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti‐resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.