Link Relevancy ,

Do search engines spider the same way as humans

[aerosmith]

My question is how do I ensure that my links stay focussed on the theme ,for example if I had a birthday card site the natural thing would be to exchange links with birthday parties, birthday supplies web sites , also kids parties and birthdays , zodiac and horoscope related web sites , so this could go on and on and the target sites could include also gift items , and shopping sites .My question is how would the google ..or any SE spider this and accept the really relevant ones( Which it deems fit ) .Inshort does the search engines evaluates the links as the same way as humans, or have a different procedure?
Also is having unrelated web sites constitutes a link farm by google?..

[fathom]

Welcome to WebmasterWorld aerosmith. :)

The link anchor is primarily what determines relevancy between pages of a site and between sites, and text in the immediate vicinity of the link is believed to also be part of this weighing process.

A vast assortment of off-topic links is unwise, not so much that you would be considered a link farm, but more to diluting your theme of topics.

Links farms are essential very complex exchanges of links, 100's to 1,000's of links weaving between sites (cross-linking) and this is why "a bad neighborhood" and penalties/bans occur.

[aerosmith]

Thanks Fathom . Can I change the link text (the title to suit my preference ) for example if a site focusses on perfumes , can I write the link text as birthday gifts-perfumes .Is that acceptable with google?..?or does that constitutes a spam .
Also what should I give importance to while exchanging links .Alexa rating or Page rank? . I sometimes see some sites having a very high alexa rating but a good PR .

[spherica]

I would suggest keeping the text to reflect what the page you are pointing at.

I say this, not for spamming purposes, but for "Patron" purposes.

If someone goes to that link and there is nothing to do with perfume they might not come back to your site. For the reason of not giving proper info.

Does that make sence?