What does 'flap' refer to in phonetics?

In phonetics, the term 'flap' specifically refers to a type of consonant sound that is produced quickly. It commonly occurs in certain languages, including American English, where the /t/ and /d/ sounds may be articulated as a quick tap or flap of the tongue against the alveolar ridge, the area just behind the upper front teeth. This sound is heard in words like "butter" or "ladder," where the 't' or 'd' sounds are pronounced with a single, rapid gesture of the tongue, rather than a full closure like in a standard /t/ or /d/. This rapid articulation is what distinguishes the flap from other consonant sounds, making it a unique feature of speech in various dialects.