The term lyric poetry encompasses a broad range of different styles and formats, which makes it difficult to isolate overarching characteristics. (Sonnets, odes, and elegies are all examples of lyric poetry). That being said, lyric poems are always expressive: they are written from a first person perspective, and are revelatory of the feelings and thoughts of the speaker. Lyric poetry is therefore highly subjective in content. These poems are also characteristically short, though odes tend to break this general rule. This brevity leads to intense imagery and strength of language, for much must be said in a small space. Most of the works typically studied in school are lyric poems—poets such as Emily Dickinson, Edgar Allan Poe, William Wordsworth, Shakespeare, and Robert Frost all write lyric poetry. As you can see, the range and times that the genre spans are great.
So, we can safely generalize and say that lyric poems are usually short, subjective in their expression of thoughts and feelings, and from a first-person point of view.
Often lyric poetry dwells on brief moments and less substantial elements of life, whether as an event unfolding as the poem unfolds, or as a memory or recollection.