This review summarizes 40 years of event-related potential (ERP) studies on emotional processing using pictures that vary in valence (unpleasant-to-pleasant) and arousal (low-to-high). ERP components are primarily modulated by affective stimulus factors, with little change in peak latency. Arousal effects are consistently observed at longer latencies, while valence effects are inconsistently reported across latency ranges, including early components. Affective ERP modulations vary with recording methods, stimulus factors, task relevance, and emotional state. Theoretical issues, stimulus factors, task demands, and individual differences are discussed. Affective processing is linked to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced processing of arousing pictures is associated with memory encoding, with task-induced differences contributing to emotional reactivity at later components (>300 ms). ERP studies using the International Affective Picture System (IAPS) have shown that affective content elicits more attention than neutral conditions, with amplitude modulations observed in early and late components. Valence influences early components (100-250 ms), while arousal influences later components (200-1000 ms). These effects are observed in both passive and active tasks. The P300 component, part of the long-latency ERP, is associated with attention and memory storage. Arousal-related ERP modulations are influenced by task demands and stimulus evaluation. The slow wave component is related to task demands and working memory. Valence and arousal effects are influenced by stimulus motivational properties and attentional resources. Arousal is linked to enhanced memory encoding and long-term memory storage. The P300 component is influenced by task relevance, motivational significance, and arousal level. Valence effects are more pronounced for unpleasant stimuli, while arousal effects are more pronounced for arousing stimuli. ERP studies show that affective processing begins early, remains sustained, and occurs across multiple processing stages. Theoretical implications include the "negativity-bias" framework, which emphasizes the intrinsic relevance of unpleasant and threatening stimuli. Arousal-related ERP modulations are influenced by task demands and stimulus evaluation. The P300 component is associated with phasic activity of the locus coeruleus-norepinephrine system. ERP studies also highlight individual differences in affective reactivity, including gender, age, and cultural factors. These findings suggest that ERP studies can provide insights into the neural mechanisms underlying emotional processing and memory.This review summarizes 40 years of event-related potential (ERP) studies on emotional processing using pictures that vary in valence (unpleasant-to-pleasant) and arousal (low-to-high). ERP components are primarily modulated by affective stimulus factors, with little change in peak latency. Arousal effects are consistently observed at longer latencies, while valence effects are inconsistently reported across latency ranges, including early components. Affective ERP modulations vary with recording methods, stimulus factors, task relevance, and emotional state. Theoretical issues, stimulus factors, task demands, and individual differences are discussed. Affective processing is linked to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced processing of arousing pictures is associated with memory encoding, with task-induced differences contributing to emotional reactivity at later components (>300 ms). ERP studies using the International Affective Picture System (IAPS) have shown that affective content elicits more attention than neutral conditions, with amplitude modulations observed in early and late components. Valence influences early components (100-250 ms), while arousal influences later components (200-1000 ms). These effects are observed in both passive and active tasks. The P300 component, part of the long-latency ERP, is associated with attention and memory storage. Arousal-related ERP modulations are influenced by task demands and stimulus evaluation. The slow wave component is related to task demands and working memory. Valence and arousal effects are influenced by stimulus motivational properties and attentional resources. Arousal is linked to enhanced memory encoding and long-term memory storage. The P300 component is influenced by task relevance, motivational significance, and arousal level. Valence effects are more pronounced for unpleasant stimuli, while arousal effects are more pronounced for arousing stimuli. ERP studies show that affective processing begins early, remains sustained, and occurs across multiple processing stages. Theoretical implications include the "negativity-bias" framework, which emphasizes the intrinsic relevance of unpleasant and threatening stimuli. Arousal-related ERP modulations are influenced by task demands and stimulus evaluation. The P300 component is associated with phasic activity of the locus coeruleus-norepinephrine system. ERP studies also highlight individual differences in affective reactivity, including gender, age, and cultural factors. These findings suggest that ERP studies can provide insights into the neural mechanisms underlying emotional processing and memory.