Data Siphons spawn on each sector, and can be picked up by occupying the same space as them. You can also acquire Data Siphons by SIPH+ ability.
They are used in order to gain abilities and to get Energy and Credits from tiles. You cannot use another data siphon on a tile that you stood on while siphoning, but you can use it on an adjacent tile that was siphoned from.
Siphoning affects the tile you are standing on and every tile/block horizontally or vertically one tile away, in a cross pattern.