A tongue-twister is a sequence of words that is designed to be difficult to articulate properly. Usually, it is used as a type of spoken word game that each participant tries to recite it as fast as they can. It could generate a lot of fun and laughter especially when the speakers keep making the same mistakes.
English tongue twisters can also be used by students of English to improve their pronunciation and accent. To make it really beneficial, a student should first make sure that he/she is saying it correctly before trying to speed it up. This can be done by consulting a native or fluent English speaker if possible. If no such help is available, one could try to imitate a video or audio recording of a teacher. In any case, it would also be a good idea to try some self-correcting by listening to your own sound with the help of a recording device.
Try some of the links below to get the fun of learning started.