The TCP header is the first 24 bytes of a TCP Segment.
☝️ TCP header as defined in RFC 793
Each row has 32 bits (4 bytes) with 6 rows giving 192bits (24 bytes) in total.
In the first row, we have:
In the second and third rows, we have:
Setting a flag bit means setting its value to 1.
From left to right, the TCP header flags are: