The participle is perhaps best thought of, at least in some of its uses, as a verbal adjective - it performs some of the functions of a verb, and some of the functions of an adjective. (The balance between these two changes in different contexts.)
There are two verbal participles in English: (for more on the strictly adjectival participle, see Participial adjective)
- One is often called the present participle, sometimes the 'active participle'. It always ends in -ing. (It is not only easier, but technically more useful, to call it simply the -ing participle, which shows clearly how it is formed, eg "to carry", "carrying".) Although it has several uses, it is clear which form of the verb is being used. (The verbal noun takes the same form; but the distinction is academic - i.e. not important - unless you are a grammarian.) You can't easily mistake it for any other words.
- The second is sometimes called the past participle; sometimes the 'passive participle'. (Again, a simpler name for it is the -ed participle, although one of the commonest of the irregularities among English verbs is when the past participle, or past tense, or both, end in letters other than -ed.) This is not the same as the past tense - though for regular verbs it looks exactly the same. When a verb form ending in -ed (or an equivalent) is used as a verb on its own - e.g. 'He curried the vegetables' - it is the past tense. When it is combined with the auxiliaries have or be - e.g. 'He has curried the meat', 'the meat was curried' - or used in a more free-standing way - 'curried, the meat was delicious' - it is a participle.
Usually, in English, adjectives go before the noun they describe (e.g. "a green car", "a bright student"). Participles are much looser in the position they can take. "Running for the bus she tripped" and "She tripped, running for the bus" are both completely well-formed sentences, and their meanings cannot be distinguished.
For discussion of a common error, see hanging participle.