Circular RNAs (circRNAs) are a type of non-coding RNA molecules that lack a 5' cap and a 3' poly(A) tail and form a circular structure with covalent bonds. Distinct from traditional linear RNAs, circRNAs possess a closed circular structure and are abundantly present in the eukaryotic transcriptome. The majority of circRNAs are composed of exon sequences and exhibit conservation across different species, as well as tissue-specific and expression patterns of developmental stage-specific.