Ellie
Birmingham (and large town) directories
Directories were issued by firms , mainly as an aid in finding businesses. In later years (post 1875) private addresses were incorporated also, but were not so well covered, particularly in poorer areas. People in back houses were usually only listed as a trade, not if they just lived there. All the most recent directories were Kellkys, but ealier ones were Slaters, Whites, Corporation or post office directories. Other areas had other firms. People went round compiling them. If no one was there, or they got a flea in their ear, then a place would be missed out. Thus somewhere could be in one year, out the next two and then in again. Not being listed doesn’t mean its not there. Early ones were not issued yearly. The date on the directory is the issue year and usually can be taken to refer to the year before.
There was usually a short description of the area, and a section on local institutions, schools, hospitals, railway stations, etc. Also a section listing firms and individual people in business and another listing by occupation. If you were looking for a publican, he would be listed in the “firms and individual businessmen” but the pub would be listed under public houses, or in earlier years under licensed premises, or inns . One problem is that some pubs (usually ones with only a beer licence) were not always listed under their name, though this was less common more recently. Recent (post 1870 and many before) also had listings by road and for private addresses.
Directories outside big towns
These are not always so useful. You usually have to search each individual town or village. There is no listing by road, and in earlier directories the full address is not given for an entry, probably because there were no numbers normally used as everyone knew where a shop or whatever was in a small town.
Hope that gives you some idea and is not too complicated. Typical entries are given below for an entry by street, by name and by occupation:
mike