SWC files (file extension of .swc) are text-based (ASCII text) files that describe three-dimensional neuronal or glial morphology. These digital reconstructions represent morphology as a vectorized tree structure, made of a series of connected nodes. An SWC file contains a series of text-based rows where each neuron node is described by a single row of only seven space-separated values. The format is simple and intuitive; a parser of or writer to the format could be implemented by anyone with knowledge of any programming language.

Links:

Documentation: https://swc-specification.readthedocs.io/en/latest/swc.html     
Github: https://github.com/INCF/swc-specification

Similar Standards:

MBF File Format 4.0, Amira, Neurolucida ASCII, SNT

Publications:

Cannon, R.C., Turner, D.A., Pyapali, G.K., Wheal, H. V., 1998. An on-line archive of reconstructed hippocampal neurons. J. Neurosci. Methods 84, 49–54.   
Link to the publication 

Nanda, S., Chen, H., Das, R., Bhattacharjee, S., Cuntz, H., Torben-Nielsen, B., Peng, H., Cox, D.N., De Schutter, E., Ascoli, G.A., 2018. Design and implementation of multi-signal and time-varying neural reconstructions. Sci. Data 5, 170207.  
Link to the publication