Phenolic compounds are a diverse group of phytochemicals classified into flavonoids, phenolic acids, lignans, coumarins, phenols, phenylpropanoids, quinines, stilbenoids, and xanthones. Flavonoids, which make up the largest cadre among phenolics, are further subdivided into anthocyanins, flavanols including proanthocyanidins, flavonols, dihydroflavonols, flavones, isoflavonoids, flavonones, chalcones, and dihydrochalcones. Phenolic acids are further subclassified as hydroxybenzoic acids, hydroxycinnamic acids, hydroxyphenylacetic acids, and hydroxyphenylpropanoic acids. Other phenolics include alkylmethoxyphenols, alkylphenols, curcuminoids, furocoumarins, hydroxybenzaldehydes, hydroxybenzoketones, hydroxycinnamaldehydes, hydroxycoumarins, hydroxyphenylpropenes, methoxyphenols, naphthoquinones, phenolic terpenes, and tyrosols. Food databases specifically on phenolic compounds include the Phenol-Explorer, USDA-Iowa State University database for isoflavones, USDA database for flavonoids, and USDA database for proanthocyanidins. The phenolic content in foods can be obtained from these accessible databases. The occurrence of phenolics as well as concentration in foods is summarized based on the current literature. In this chapter, we have provided an update of phenolic compounds and their concentrations in foods based on recent studies. Cloves, cocoa powder, dried peppermint, star anise, dried Mexican oregano, celery seed, black chokecherry, dark chocolate, flaxseed meal, and black elderberry are among the top foods abundant in phenolics.