If you mean how even numbers are on one side of the street and odds on the other, then this is because it is a standard convention in this country and many others. Numbering also tends to start from that end of the street which is nearest the centre of the conurbation (village, town, city) and work away from it. You will, however, see examples where the numbers go consecutively in odds and evens up one side of the street, often because there is no development on the other side which lends itself to numbering, if any at all, and also where once numbers get to the far end they continue back on the other side to get back to the starting point on the other side of the street. I rather think these are old numbers from before the adoption of the "standard", possibly an attempt to be "cool", "innovative" or "imaginative", etc.