what's mean battery pack -The Button Cell ?

what's mean battery pack -The Button Cell ? what's mean battery pack -The Button Cell ?
The button cell was developed to miniaturize battery packs and solve stacking problems. Today, this architecture is limited to a small niche market. Non-rechargeable versions of the button cell continue to be popular and can be found in watches, hearing aids and memory backup. The main applications of the rechargeable button cell are (or were) older cordless telephones, biomedical devices and industrial instruments. Although small in design and inexpensive to manufacture, the main drawback is swelling if charged too rapidly. Button cell View the rest of this article