Participles in Czech grammar are verb forms that combine characteristics of both verbs and adjectives. They can be used to form compound verb tenses or as adjectives to describe nouns. In Czech, there are two main categories of participles: active and passive. Active participles are formed by adding “-ící” or “-íc” to the root of the verb, while passive participles are formed by adding “-ný” to the verb root. Understanding and using participles correctly is essential for mastering Czech grammar.