I generally use the EMA (exponential moving averages) but some traders use the SMA (simple moving averages). The difference is that the EMA puts more emphasis on the action in the more recent days, where a simple average adds up the closing prices of the prior 50 days, and divides by 50.

Right now the S&P 500 (C-fund) and the DWCPF (S-fund) are on opposite sides of their 50-day SMA. The S&P is struggling to get above while the DWCPF broke above it on Monday, and now that is trying to hold it as support.