To provide appropriate relevant content to the users and visitors of any website, number of inbound and outbound links is very important; your link to any other relative webpage will provide the ease for the visitors to get specific content which they wanted to get. This increases the value of the link and also page. Value of any link is decided through the number of satisfied visitors.
Some important factors that very closely affect the link value are-
1) Anchor text
Anchor text is the text that is visible on behalf of the link, it represents the aim of the click-able portion or the content of the link. Search engine uses this anchor text to understand what is the link receiving page is about.
Links that originate from sites/pages that are relatively similar to those of the existing site are more worthy than coming from the sites/pages which are completely different.
Authority refers to some trusted websites that search engine consider relevant according to specific topic, also there is one term used in presence of authority i.e. hubs, hubs are websites or pages that point (link) to the authority websites. You will never know about which are the websites that search engine considers as authority sites. You need to link to good authorized sites by your own strategy.
Trust for any site is decided on the basis that whether other trustful sites link to that website, more the links from other trust worthy sites, more the trust gained by a particular site. This helps search engine in filtering the spammers.