I first googled 'Semantics', 'Algorithm' and 'Freethought' and opened the Wikipedia on each subject on a tab each. Somehow, I went from 3 tabs to 8 tabs crowding my chrome browser( along with 13 other pinned tabs on sculpting and photography). 
Semantics branched to semiotics and denotation and semasiology. 
Algorithm ( which I am totally clueless as to the meaning of)  branched to pi - because I didn't know the relation between the two, axiom, first-order logic, Entscheidungsproblem, circumscribed circle, Democritus and Thales - the two fathers of science, Anaxagoras, tangent, trigonometry -which I just found out is the study of triangles and Q.E.D. Freethought branched to Pantheism, List of Deists, Anaxagoras, naturalism, sufism, etc. 


And this is why I partially hate Wikipedia. ( I partially blame myself for not knowing the 'simple' terms therefore having to open them in new tabs which branches to new tabs as new terms come along within that subtopic. )