__name__ and __main__ in functions

[Mark17]

Here's a short program:

lwords = ["a", "an", "and", "as", "at", "but", "for", "how", "if", "in", "of", "off", "nor", "or", "so", "the", "to", "up", "via", "with", "yet"]

def make_title(sT):
    rlist = []
    rs = ""
    for word in sT.split():
        if not word.isupper() and word not in lwords:
            word = word.title()
        rlist.append(word)
        
    if not rlist[0].isupper():
        rlist[0].title()
    if not rlist[-1].isupper():
        rlist[-1] = rlist[-1].title()
        
    for word in rlist:
        rs += " " + word
        
    rs = rs.strip()
    return rs

def main():
    sT = input("Enter the title: ")
    print(make_title(sT))
          
if __name__ == "__main__": #infinite loop results with L26 and L27 uncommented.
    main()

I can follow the logic until the last two lines. What do __name__ and __main__ do with regard to [this] function[s]?

Actually, I guess main() is a function defined to contain the main function so no mystery there. What is this __name__, though?

Thanks!