A simple definition would be the opinion we have of ourselves. The level of self esteem we possess is core to our perception of personal worth and at some time or another probably every one of us has to cope with low self esteem.

Your definition might well be different. For you self esteem might be about being confident and happy or it may be linked to success, wealth or power. While these attributes are linked to self esteem, they don't guarantee it.

A more complicated definition might suggest that Healthy Self Esteem is an enduring sense of oneself as a fundamentally valuable person.
Effective Strategies for Increasing Self Esteem

First recognise that it won't happen overnight and you will need to work at it.

All of us love to rate and compare. We may say "that was a great meal" or "that was a dismal film". If you rate yourself globally based on a few aspects you are engaging in a problematic process that will result in your opinion of yourself going up and down.

For example getting a promotion at work = I am a winner, the next day your girlfriend breaks up with you = I am loser. Recognise that neither is true, you are just a person who is capable of success and failure and you are far too complex for a simple global unidimensional rating.

Recognise that you are not static and you change and grow throughout your life. You will evolve personally, acquire new skills, new interests, new priorities, new friendships and new hopes and dreams.

Some changes are good, some not so good. You will never be able to sustain one view of yourself as you are in a constant state of flux and ever-changing. Recognise that by accepting yourself you also accept others. Accept failures in yourself and in others by having a compassionate attitude towards yourself, especially when things are not going well. This will translate into your relationships with others and healthy self esteem will result.

Accept your limitations and be realistic about your self development. Your self esteem will benefit when you invest in areas where you are most likely to reap results. Change may be difficult but not impossible, don't be prevented from embarking on your journey by negative feelings caused by low self esteem.

Good news!

Increasing self esteem is something that you can work towards and achieve. CBT is an excellent therapeutic modality for low self esteem as the problem is primarily a cognitive one, in that we "think" ourselves into low self esteem. Do yourself a favour and get some help and have a good life.