Extracting data from a particular tag in html

Hi Everyone,

My requirement is that i have around 1000 companies websites and i have to find their list of services which each company provides for each company by going to their websites. It might happen that in some company website they might not have provided their services.
I thought of a solution that i will download the html tag for each company website and will try and find the service tag if there is any service tag may be one or ten i have to extract data from that service tag.
i am able to download all companies source code (html) but after that i dont know how to find that service tag present or not and if present then how many service tag present and extrat data from all of them.