What is the best way to get keywords from some web page according to its content, i.e.
if we got web page in which we have article regarding the new phone from Samsung or Apple (it doesn't matter)
so what i need is some crawler that can take keywords from that article and than if i will give him some
text it could parse it and associate it with some category according to the keywords it got, for example if
text has keywords like: [phone, technology, internet ...] it will associate it with category technology and so on .
So my question is if i should, in my case, to create/develop it from the scratch , if so from what is better to start?
or is there any technology that already got something like this ?