Granny squares are a great fundamental in crochet and super easy to learn. Once you have the technique down, you can use it as a building block to make all sorts of fantastic creations!
Below is the the tutorial I created in honour of Granny Square Day!
Make a magic ring or ch4 and join.
Chain 3, work 2dc into loop, chain 2 (this will make a corner), work 3dc into loop, ch2, 3dc, ch2, 3dc, ch2, join to the top of the beginning chain.
Row 2. Join new colour in one of the corner chain 2 spaces.
Ch3, 2dc in ch 2 sp, (3dc, ch2, 3dc) in next 3 corner spaces, 3dc, ch2 in starting corner and join to top of ch3 with a sl st.
Row 3. Join new colour to corner. Ch3, 2dc in corner. 3dc in the gap between the 23dc clusters from the previous row. *(3dc, ch2, 3dc) in next corner, 3dc in gap between 3dc clusters from previous row. Repeat from * 3 times. 3dc in starting corner, ch2 and join to top of ch3.
You can continue in this way round after round. The increase always happens in the corners and you will work more 3dc clusters in the gaps between the ones in the previous row.