If you’re documenting an entire website or web project, provide a date range in your works-cited-list entry when the website provides one:

Centre for Editing Lives and Letters. U College London, 2003-14, www.livesandletters.ac.uk/.

If the website provides more than one date, provide the date that is most useful. In the example below, where a date range and date of last update are provided, the date of update is likely to be the most useful because it tells your reader the currency of the information (an exception might be if you are using the source to make a historical point about changes to the site over time):

Piers Plowman Electronic Archive. Edited by Robert Adams et al., Society for Early English and Norse Electronic Texts, 8 Mar. 2018, piers.chass.ncsu.edu/.