Abstract
High resolution images reveal that a thread-like structure, with typical width of 0.3 arcsec, is the fundamental element of solar filaments. There is strong evidence that these threads are field- aligned. I present an empirical model showing the observed properties of filament threads in spine, barbs. High resolution H-alpha images in time series show filament threads swaying back and forth with a period of 3-4 minutes. Temporal variation of the Doppler velocities also show evidence of waves propagating along individual threads and along a group of threads as well. The corresponding oscillatory periods are 3-9 min. Kink magnetohydrodynamic waves are proposed as an explanation of the observed thread oscillations