Most people these days play a short club with a strong no trump and five card majors, therefore opening 1 club is quite often a weak no trump holding.
The Landik conventional 2♣ bid describes a 5-4 or 5-5 holding in the majors up to about 9 points after the bidding has gone… 1♣ from partner and a strong 1NT overcall from the opposition. Now you bid 2♣ hoping to find a fit in the majors.