Display teas (or "blooming teas" or "flowering teas") are meant to be enjoyed for the "show" they present while steeping. Depending upon the size and shape, they can be steeped in a wine glass or clear glass teapot. The idea is to watch the tea open/flower/bloom as it steeps.
Generally speaking, display teas are young tea leaves that are bunched and hand-tied or rolled to create distinct shapes. The shapes themselves are interesting even before steeping begins. Once in the water, the leaves unfurl to create a completely different shape. Some display teas are all leaf, but some contain colored flowers that are slowly revealed.
Because display teas take some time to unfurl, and are usually left in the glass or pot while drinking the tea (don't worry - because they are tied together, you won't swallow a clump of tea leaves!), these teas are usually made with specific varietals of tea that will not get bitter.
I always use a display tea in my tea classes because people are so amazed by them! They should be - display teas are unique!